As I am sure you know the issue with McCain was not that he was captured.
The issue is what happened after McCain was captured—his father’s role etc.
President Trump’s remarks were typical “shorthand”—not the way I would have worded it for sure—and it is such a delicate subject probably would have been best not to go there at all.
No fan of the duplicitous McCain am I.
Part of being Presidential is to think before you say things, and "I like people that weren't captured, OK?" goes beyond, beyond "OK".
His verbal swipe at DeSantis will likely ire more undecideds than convince to favor Trump.
In the 2020 primaries, Trump had the tailwinds of a fairly successful presidency and the fact that the incumbent is the de facto nom.
This time? He, and everyone running (and it'll be a large group of moderates, RINOs, and Trump and DeSantis) will need to convince GOP voters that he is the best choice. In some ways, it's his to lose, as many Trump voters have a strong attachment (not a bad thing). In other ways, and paraphrasing the never-Trump WSJ, Trump continues to be his own worst enemy. Voters, like me, who believe that competition between the two front runners will reveal the better nominee, observe that Trump might be blowing it early.