Noam Chomsky might have said "the only statesman who could stop the war was Trump" but that doesn't mean he would have been able to (or even wanted to).
I would prefer to listen to John Mearsheimer when it comes to analysis of the Ukraine war (and sometimes Scott Ritter).
US Foreign Policy is at a higher level than US Presidents. It doesn't matter what a certain US President wants, it's what the Empire demands.
If you think for even a second that Trump is interested in anything but himself, I think you may have misjudged him. If the war with Russia was in his interest, he would be all for it. If not, he would not. It's that simple.
Trump is not a complicated man. He shouts it out from the top of the mountain about his narcissistic & egotistical personality all the time - if you fail to see that, you may have succumbed to confirmation bias.
There have been so many books written by reputed journalists and authors (that Trump himself authorized) that makes it evidently clear that he has been this way all his life (check out his whole history from the beginning - his behavior as a president has been no different from anything else he has done in his life).
To me, pointing out that Trump is interested only in himself (and some members of his immediate family) is like pointing out that Israel is a Zionist settler-colonial project.
But besides our pontificating on what Trump would or would not have done, it really doesn't matter in the end - as US Foreign Policy is decades in the making and supercedes the actions of any one administration or political party.