Old Tom Morris said:
You seem to be missing a critical difference - we aren't saying it's the smartest, most careful thing to show his face. We're simply saying that this is how his character operated throughout the series. It was dumb to bring Jesse in. It was dumb to try to kill Hector personally. Those things got him killed. He was cautious. But not perfectly cautious. He got his hands dirty in running his business. That was his character.
And you're right, it is an extremely complicated project. All the more reason for him to feel like he needs direct involvement.
I think it's out of character. At first he wasn't going to do business with WW because he was associated with a junkie. It was only WW's persistence and the quality of his product that made Gus change his mind. Gus knows WW cannot turn him in because WW would himself go to jail. They are in on it together.
There is no reason to believe such relationship between Gus and the manager of this construction project. This guy could quote a price, meet Gus, start work, then a month down the road become suspicious that it's for some drug activity and turn Gus in. Especially if he is afraid that he might get killed afterwards. Unlike WW or any of the other thugs, the construction guy is not at risk to go to jail because all he's hasn't been doing anything illegal. Unlike meeting WW, the cousins, cartel, etc. having this guy knowing that Gus is into illegal activity puts him at high risk.