It could have scared him and shaken him a lot. He has pretty much been top dog throughout the competition thus far. He hasn't really been super arrogant about it, but he may be questioning his own ability after being in the bottom. From where I sit, it would be silly because his dish was basically good, just a little flawed, but if he is a perfectionist and used to being on top, who knows, this soon after the shake up he may have just wanted to focus on redeeming himself by putting out the best food possible.
Add to that that it appears the EC has to manage and bears some responsibility for all the dishes thats kind of rough. Especially with that team. Katie and Katsuji are very hit or miss. Katie has made some great dishes, but she has also put out some stinkers. The same with Katsuji -- and Katsuji also seems like he can be tough to work with. As for KeriAnn, she has been more misses than hits I think, and I also get the sense that she may be prone to over-embellishing and over-stating. She said she would be great at FOH because she, at 22, had opened up her own restaurant on a cruise ship. Even if thats not the most identical experience, if she opened her own restaurant on land, sea or on a Zepplin she should have known how to train waitstaff, or at least if she needed a runner. So, I don't know.
I think old Gregory, the one who put his hand up and said that Aaron wouldn't have gotten away with whatever, would have had the confidence to take on being EC. I think for this challenge, Gregory maybe just wanted to assure himself that he could still put out great food. I think his doubts may have him in his own head too much, because his dishes looked good, but not as good as some of his other stuff.
I hope he snaps out of it soon, because I'm still rooting for him.