I don't at all like the way Ohtani handled things. To me it came across as arrogant and callously indifferent to the teams that worked hard to put together just the right pitch, in the case of the Mariners seriously rework their assets, travel all the way to LA, only to be told never mind. On that I agree.
I approach things a little differently with regard my motivations for rooting against Ohtani. I root against him because he's a key player for a division rival. I don't wish him harm, just a lack of success, a lack so pronounced that it contributes to the Angels finishing behind the Mariners.
As a man, I root for him to let go of whatever impulses drove him to his arrogant behavior.
As a historic MLB player, I root for uniquely talented players to come along, because they are a huge part of what makes the sport so compelling.