You are correct that neither replaces the other.
To fly under 44809 you require TRUST.
To fly under Part 107, you require a Part 107 remote pilot cert.
But you are incorrect when you claim that a Part 107 pilot operating under Part 107...
In case anyone reads this in the future, this is incorrect.
If you wish to fly recreationally under 44809, then you require TRUST.
If you have a Part 107 certificate, you can fly recreationally under Part 107, in which case TRUST is not...
I see you asked quite a while ago, but didn't get much of an answer. I'm a Canadian who regularly flies in the USA.
In Canada, having a sub-250 drone exempts you from the requirement for a pilot certificate and registration. You can also fly...