I think the reason is much simpler and much more selfish, Trump is simply angry Putin is doing so terribly at the war in Ukraine. It is making Trump look weak, so he has to host a UFC tournament to try to restore that rightwing toxic masculinity vibe.
I am not kidding, I think Trump is actually genuinely afraid to be seen as close to Putin based on what Trump is hearing about the strategic position Putin is placing Russian forces into from Trump's own military staff.
The winds have changed and Trump is a coward. Why the hell would people expect Trump to come to Putin's aid when Putin looks weak? Trump doesn't help weak people, he is far too weak himself to do that and retain power.