The wider issue is that Trump is wrong about everything more often than by chance.
It could be the controller was doing the work of two. However the big issue that has surfaced before, is that military aircraft communicate on UHF and the civilian on VHF. Due to this fact it has been known for a long time that there can be communication issues between civilian and military aircraft. UHF is much easier to encrypt and can keep communications more secure. But this issue has been a concern for some time, and quite likely was a factor to some degree in this tragedy. The problem with UHF for civilian aircraft is its shorter range. I think though they need to get on the same system which probably means UHF for all. That likely would require more repeater transmitters, and howls of NIMBY from those near the required masts. Most military aircraft do also have VHF capability, but it is awkward and not seamless.