Jeffrey has an abrasive personality, but he's obviously a talented designer.
But none of that has anything to do with whether or not it's appropriate for him to be investigated for a possible violation of the competition's rules. If there's an honest suspicion that he, or ANY contestant, cheated, then it should be investigated.
On a side note, remember that last night's episode was taped after this season's show had already started airing. Even Uli, when she saw Jeffrey, asked him if people were throwing eggs at him. Also, last night's episode was taped after the "scandal" had already broken, so I think some of the comments made by everyone on the show need to be viewed with that in mind.
The fact that New York Magazine quotes Tim Gunn as saying that Jeffrey's "collection was very ambitious, I wasn't born yesterday." indicates that Tim himself was suspicious of Jeffrey.
I'm not a big Jeffrey fan, but I really hope he didn't cheat. That would be beneath him, and would be a terrible example to be setting for his little boy.