A big part of MAGA and Trump's support was anti-interventionist and anti-war. The Democrats were warmongers, and he was the candidate of peace. It was the excuse some former Democrats, such as Tulsi Gabbard, gave for switching sides.
Gabbard now says
Iran would produce a nuclear weapon in weeks after previously saying, in March, they were nowhere near a bomb. So she has flipped.
It's going to be interesting to see who sticks with him and who doesn't now. To be fair, I have seen some of them flip and condemn Trump. There are many now though who suddenly think the US should intervene.