If you have to kill someone, sure, that's a moral position we can discuss. No one should ever be celebrating it, particularly when others died in the process
I don't think it overly matters anyways, though; it's not like Republicans would go "Oh darn, foiled" if Trump couldn't be Speaker. Traitors gonna treason and coup, one way or another, and it's going to be boots-on-the-ground organizing that stops them, if anything stops them.
His experiments were successful, so. At least he's not the Green Goblin