I think there is a marked difference in Trump's rhetoric v Mamdani prior to the meeting at the White House and after.

I think you are extrapolating a bit too far from an outlier data point. Trump has had several other meetings (eg. Zelenskyy) go sideways for no apparent reason.

and he has had several meetings change his opinion of the other party for no apparent reason (eg zelensky

extrapolation is futile