Pep owe nothing to Barca. He did his job as a player and manager and moved on. Don't see where the 'not very loyal' argument comes from. Yeah, he took some of his old staff with him, he had the right to do that as well, and probably did the right thing considering how this board have worked on erasing everything he did by getting rid of people without any reason whatsoever.
He also bought a former Barca player in Thiago, but why not? He would have left anyway because he wanted more playing time and not be 4th on the so called merit list where even players out of form or playing with painkillers would be ahead of a fit and healthy you.
He had personal ambitions, but who does not? Everyone have so. That doesn't mean that he is disloyal in any way.
Mourinho having more loyalty than him? Care to explain?