Well as far as i remember Ella didn't send Kenny to the party, she didn't bother to stop him when he did, from my understanding she "left" Mc to take care of him as some sort of test or challenge. The other jock from what i remember was transformed by her and was turning into a monster so this one she did stop.
Now as for your question of "how is that even a debate" i have an example, on the movie Whatchmen a character named Ozymandias detonates a series of bombs across the world in large cities, a horrible and vile action, with the intention to unite USA and USSR against a common enemy and stop a nuclear war, a noble and valid goal.
On Ellas point of view, as she will eventually explain, things will get far worse than now when she reaches her goal, but ultimately the world will be a much better place than the alternative. Since we still don't know what the fuck this even means you will find people both defending and accusing her.
In terms of consequences, she will suffer then, not by Mc's hands , but i believe you will have the chance to stop her eventually. Mc is capable of fighing her (and even putting up a worthy fight) but she is far to powerfull to be defeated by him, for now.