I've been through the "This radio is junk" thing before.
It was when I migrated our users from a Motorola trunked system to a Kenwood trunked system.
When I asked them end users that complained what the issues were, there weren't any. It was pure brand loyalty. People that do not understand radios will often blame the brand name. Motorola is believed to be better due to seeing it on TV, brand name recognition, or in some cases, previous experience. Before they changed them to the Icom's, I'm willing to bet your friend had never heard of them.
5 watts FM for a Motorola is no different from 5 watts FM from an Icom, if both are working to factory spec.
And chances are if you peeled the Icom label off and stuck a Motorola label on the radio, suddenly it would work better. Been there, done that, and it works every time.
Issue will come when they migrate to NXDN. The HT-1000 won't do that, and he'll need to have the Icom radio in hand. Make sure he hangs on to it.
If he's concerned about issues with his company issued radio, he should talk to their radio techs. They can easily put it on a service monitor and confirm it's working to factory specs. If there's a problem with the other infrastructure and other employees are complaining, then they need to let someone know so it can be fixed.
As for you programming the radio, there are several FCC Part 90 rules that would work against you.
Specifically:
90.403 says that the licensee is responsible for all radios used under their license. This is why the employ their own radio techs, to make sure everything works within the limitations of the company license. You, not working for the company, are putting an unauthorized radio on their radio system. If for some reason it didn't meet specs and caused interference to another licensed user, the company would be held responsible. They'd find the bootleg radio and start asking questions. If your buddy rats you out, then they have you by:
90.427 and 90.433, which again says that the company is responsible for maintaining radios, as in "... the responsibility of station licensees to maintain control over the stations licensed to them" and "the responsibility of station licensees to have and to maintain control over the stations licensed to them". You not being an employee of the company will get you on the wrong side of the FCC for programming frequencies into radios you are not authorized for.
Yeah, FCC isn't going to come and bust you, but if they do, it's usually expensive and they start looking at what other licenses you have.
So, just make sure your buddy doesn't rat you out if something goes wrong.
As for programming the radio….
Make sure you figure out if they use any sort of radio ID scheme, like MDC-1200, DTMF, etc. Make sure you program the new radio to match.
I'm not fooling myself into thinking anything I wrote above is going to change this situation, so at least make 100% sure you've programmed it all correctly and you cover all your tracks (no pun intended.)