So uhm ok, Nexon Emergency Patch?

It's probably more that the h4x0r will get his ass banned for sure if he bans someone. Handing out bans is a very serious business.

I don't believe it's GM commands anyways since I heard that in order to access GM accounts you need a special client. (correct me if I'm wrong)

And if he wanted to do that, he wouldn't have come in the map, killed manon in a second like we've seen hackers do many times before to various bosses (HT included), and then left. He would have followed him around and whatnot, rofl.

GMS devs are not THAT dumb to let that kind of exploit slip through.