I'd say the 2nd theory - not for it was not what Gus asked, but not what Gus does. From everything Gus does you can tell he is a man who prides himself on quality and is not the cheap suit type guy - he makes the best chicken, he's the best kingpin, he's got the best meth and I think when he tries to cook himself instead of Walt he sees it as an insult as he recognises chemistry is the art and any version made by a man other than the artist is therefore a fake, inferior quality, and Gus doesn't do inferior quality, accept poor standards or accept fakes. Even the way he walks, dresses and talks, it has to be of quality and meaning, he doesn't walk around flashing cash or get big headed - he has values and respects skills. Even the people he surrounds himself with such as Mike and Saul are generally professionals in what they do, they aren't your street level guy acting up, they are people with genuine talent that can help him and can be trusted.So yeah, I think when he tried to cook himself, he made it clear that it must be Walt cooking and he will not accept any alternative by fake chemists or cheap imitations and as Walt said, it is an art in itself, magic - which he performs best.