I agree that he is a man of principle, stubbornly so. Maybe because he has held these principles so tightly and so for long, he finds it almost impossible to flex, maybe through stubbornness, maybe through principle, maybe through wrestling with his conscious. It still comes across as dithering (at least to me).
Part on the problem is that as an effective leader you have to carry the support of a lot of people with varying beliefs and standpoints. That requires compromise and consensus. Take these guidelines - he doesn’t want to implement them in full - there are a lot of people in the Labour ranks saying get it done including two of the biggest Unions - so is he putting personal politics above those of the party?
Yes he has had a lot of attention from the media, the shoeing he got when he first got in went overboard, however, ironically, probably did him more favours in terms of entrenching his core support. However he can be his own worst enemy. You yourself admitted he looked flustered and shifty. From that, and other snippets, people make their decision as to whether he is trustworthy or not (or at least capable of running the country).