I think people are being really unfair.
It is all very well to say in theory that the game is "about lying and betrayal," but it would be very different being in there, knowing the other players, forming friendships and having to betray. Yes, of course it's the game, but most of us (I hope!) don't have much practice of what that feels like - and it isn't just spread over one afternoon. It is a sustained thing.
I think he is just upright and inclined to honesty. He KNOWS that about himself, which is why he wanted to be a faithful. He tried to rise to the deceitful challenge in his own fashion when the role was thrust on him, but it just didn't work. He was the wrong choice of Traitor.
I'm not going to villify him for finding betrayal difficult. he didn't run in saying he wanted to be a Traitor, and the odds were that he wouldn't be, especially as he told Claudia that.
Incidentally, going forward, I think Claudia should pick.
But even Kenny and Maya were awkward over his betrayal of her. Yes, it's part of the game but it runs, hopefully, counter to human nature, especially where friendships are developing in close quarters. She was livid; he felt bad.
I can't see him as unlikeable because he wasn't good at that; he knew it before and knew it to the end.