I've been caught between agreeing with (3) and (4) for a long time now. But ultimately I picked three. The thing about Trump is he always tries to project an image of strength with other world leaders, except when it comes to Putin. And he has been denying collusion all along and knows that at least appearing to take a tough stance against Putin on this would undermine those allegations and thus benefit him politically. Given his phenomenal ego and need to be seen as "tough," and given that he always acts according to what he perceives to benefit him most politically, it's hard to explain his constant boot licking of Putin unless we assume he is afraid of whatever Putin might do if he doesn't.
What putin might do? What do you have in mind? Killing trump or his family? Releasing an unsavory video? Exposing his financial ties/corruption?
The fact that trump is a narcissist makes it hard for us to figure out his thinking. As a normal person, since most people are already aware of a potentially compromising tape and of a history of infidelity, it seems like the easy thing to do would be to stand up to putin and say to hell with the compromising info.
Now if it has something to do with exposing trumps corrupt finances, that's a little trickier situation to maneuver since there is a potential of being convicted of a crime and having everything taken from him.
If he's having threats to himself or his family, it would seem like the fact that he is protected by secret service, as is his family members, would render any threat useless.
But if you are compromised, would you be able to respond off the cuff so quickly with praise for your compromiser? Wouldn't body language convey some sort of uncomfortableness? Wouldn't there be contradicting statements eeked out when speaking off the cuff?