Of the options, I also think the following are possible:
1st Choice: At a time where the public is about to learn the MSM has been betraying them by taking intel leaks from the CIA daily at 4 am (Project Mockingbird still lives!), Rush needs to stay away from the appearance of accepting or utilizing intel leaks from the current adminstration(Q).
2nd choice: Conservatives are in jeopardy in the mainstream as it is; even speculating about the existence of Q would at the very least eliminate airtime.
3rd choice: He’s never heard of Q or doesn’t believe Q is legit.
Quite plausible.
I've said before that mainstream reference to Q not only jeopardizes the operation, but risks that mainstream media person being "Alex Jonesed." We all have seen even here on FR how mockery, and ridicule is used to deny facts and silence voices. It is a tried and true method of the left and it works.
Even Hannity dares not mention Q, I don't think. Our guys walk a very fine line on this.
Option #4 - This Q stuff is fringey, conspiratorial, verging on nut-case stuff. We don't need the guys publicly fighting the good fight wandering from the good work they are doing standing on the solid ground of what is clearly visible to them and their audience. As you said, we don't need them wandering into Alex Jones-land. They can stand at the entry way to the twilight zone this stuff is in, but they can't open the gate and cross in.