Well it's unknown who did it so no one can confirm or deny what. It's still a terrible thing. Also that doesn't make GC people okay or anything.
So grafitti may or may not have been done by some GC people.
All that means is that some GC people aren't nice. Actually they probably are nice, they just did a bad thing.
You know, much in the same way that Karen White doesn't mean all trans women are rapists.