There are a number of issues with doing this.
Can it be done? Yes/Maybe, a lot of variables.
Should it be done? No.
There are a number of legal issues with this. I'd suspect your 'fellow enthusiast' is an amateur radio operator?
There are no permissions granted by the FCC to amateur radio operators to utilize -ANY- frequencies that are not specifically granted under the Part 97 rules. ANF and Amateur radio frequencies are different and will not work together.
The National Forest Service operates on frequencies governed by the National Telecommunication and Information Administration, not the FCC. NTIA rules and FCC rules are different. Again, nothing in the FCC Part 97 rules grant permission to legally transmit on those frequencies in any situation.
Most amateur/hobby grade radios, especially the Cheap Chinese Radios, do not have type certification to be used outside the amateur radio bands. Transmitting with a ham or CCR radio outside the ham bands is another violation of the FCC rules.
I run radio systems for public safety agencies. I've specifically talked to our dispatchers about how they'd respond to a random person popping up on one of our frequencies. They would treat it as a hoax and likely would ignore you. They are trained to ignore interference like that. If you kept it up, they may respond, but you'll have a ton of explaining to do. For the agencies I work for, that would be followed up by a call to the FCC.
Relying on an agency to respond to you transmitting illegally on their frequencies is a poor plan. It relies on breaking several FCC Rules and likely NTIA rules. It requires programming questionable data into your radios (remember, data on the site is submitted by hobbyists, so accuracy is not guaranteed). It also relies on USFS not making any changes to their radio systems. Since USFS doesn't update their information on the RadioReference website, and the frequency information is not on the FCC website, it would be downright foolish to rely on data provided by hobbyists in any emergnecy. It also relies on a public safety professionals not treating you like a hoax. It ignores established procedures for contacting emergency services, and sort of demands that an individual with a ham/CCR radio are much more important than those that follow the established procedures. It assumes that at any given point, your radio traffic is more important than whatever else they are working on. It ties up resources that may be needed for more important situations.
A while back, someone specifically asked this question of the FCC. Here is their reply:
Question: Can amateurs modify their radios and use them in time of emergency on public service frequencies (e.g. police, fire, etc.)
This question was referred to the Wireless Telecommunications Bureau of the Federal Communications Commission (FCC). Here is their answer.
“Your question was referred to me because it concerns the Commission’s amateur radio rules.”
“Section 97.105(b) answers your question: ‘A station may only be operated in the manner and to the extent permitted by the privileges for the class of operator’s license held by the control operator.’ Control operator privileges are specified in Section 97.301.”
“Section 97.403 ‘…applies to amateur frequencies only. For example; a technician may operate an extra class frequency in time of emergency…not non-amateur frequencies.”
“Part 97 does not contain any “privileges authorized” for amateur radio operators that include Part 90 or Part 95 frequencies. Part 90 and Part 95 both require the use of certified equipment. See Section 90.203 and 95.409. Use of modified amateur radio transceivers on Part 90 or 95 frequencies violates the rules because modified amateur radio equipment is not certified for either Part 90 or 95 radio services.”
“As you note, “The rules are clear that in order to use Part 90 or 95 spectrum, the operator must have the correct licensing and certified radios to use those services.” The debate y0u are referring to, therefore, comes down to “How can we get around the rules?” The answer is, “You can’t.” We will be happy to relieve you of thousands of dollars and your amateur radio license if you transmit on channels you are not licensed to transmit on.”
As it says, Part 97 grants zero permissions to do this. Hams/hobbyists like to misinterpret the rules to suit their fantasies. It's just that, a gross misinterpretation that shows little to no understanding of the FCC rules. Hams/hobbyists will argue this forever, but the FCC has spoken and it's well established in the existing FCC rules.
If you wander into the undeveloped parts of the world, the responsibility is on the individual to be properly prepared. Relying on hacked/modified radios to transmit in violation of many FCC rules is not being prepared.
There are established means of getting help when outside cellular phone coverage. Personal Locator Beacons are specifically designed for this. They'll be treated accordingly by public safety agencies, and they'll provide useable data that someone with a CCR cannot. They are NOT expensive for what they are and the safety they offer.
Also, "emergency" needs to be well defined. An average person does not have enough medical training to properly determine what constitutes a medical emergency in most cases. Breaking in on the USFS radio system and creating a lot of issues because of a situation that may or may not be an emergency is a waste of resources and puts others lives at risk. No emergency responder wants to put their own lives on the line rushing to a scene that turns out to be something that was not worth the risk.
That said, in a true life or death emergency, saving human lives will be top priority. Making good decisions ahead of time is your responsibility. Cheaping out and relying on bootleg radios working on systems you don't have legal access to is a lack of planning and preparedness.
If your "fellow enthusiast" still insists it is legal/OK, then please have him contact the Region 5 office and get their permission in writing and kindly share that with the rest of us.