I believe your statement about how you feel President Trump campaigned in 2015/2016 has zero relevance when discussing second hand rumors of a media induced fake feud with Ron DeSantis.
You keep putting forth the idea that Ron DeSantis is his political rival with zero credible evidence whatsoever to make the “feud” nonsense seem plausible.
The problem is that your foregone conclusion that they are political rivals is a false premise and the rest of the argument fails from that point onward.
My point is not "we know he did it to DeSantis in 2021 because he did it in 2015/16.". As you correctly point out, we don't even know if Trump considers DeSantis a rival.
But that's also why I don't care about the rumors. I know that Trump did it in 2015/16 because I heard him with my own ears. So it is at least plausible.
Then again, there's always the possibility that he's changed, is a different guy than he was in 2016, and so wouldn't go after any rivals the same way. So whether this particular allegation is true or not - which we don't know - doesn't matter. All that matters is whether he actually says stuff publicly.
Whispered rumors behind the scenes are - true or not - irrelevant to me.