To be fair, while I agree it was uncomfortable and don't think Gretel's attitude toward him live on air was appropriate, Jamie tried WAY too hard to "play" the audience/house. When his acting career and training came to light on the outside, his game fell apart.
He very much attempted a Tim Brunero tactic during his time on the show (even though that particular detail wasn't public knowledge at the time). But, unlike Tim, Jamie's playing the "nerd card" all the time and during every live cross was far too transparent and just came across fake. I think it rubbed Gretel the wrong way because she, like a lot of viewers, could see right through it.
Gretel's behavior may have been uncomfortable, but in my opinion Jamie's was also just as uncomfortable inducing.