My thought on that, is that Trump is not as free as we might imagine. I think the GOP (Ryan and McConnell) has carefully explained to him some -specific- things that will cause him to be impeached if he does.
1) Prosecuting Hillary in any form...possibly even investigating her.
2) Firing Sessions.
3) Removing sanctions against Russia or imposing them on Iran.
4) Refusing the NSC to be from the approved list he has been provided.
Probably others...
