The USSS does have newer frequencies they are using other than the ones listed on RR.
They are still on VHF P25 Simplex AES encrypted. Presidents detail is now on 167.0125 and 167.0375. There are other frequencies, the best thing to do is search from 163-174 MHz and 406-420 MHz.
POTUS Detail in Michigan today was on the usual couple channels that've been in use for decades. There was no activity, related or unrelated, heard on 167.0125 or 167.0375, & monitoring assets were within... well... very close to the assets such as AF1, Marine 1, etc.
Also, those two 167MHz freqs are VERY close together -- if I was doing freq management for WHCA there's no way I'd choose ones that close to each other. Not smart, in terms of possible adjacent channel interference/de-sense concerns, for something as critical as a POTUS/NCA communications system.
Tim