I agree with some of those points but think it's not impossible but not likely that Gus will order the killing of the German workers. If he did that, his connections that got him the workers would know that anyone he hires isn't coming back and he'd burn those bridges. Also, Gus is someone who kills for two reasons, revenge and necessity. He paid the families of ten associates in prison rather than kill them, and when Walt got the laundry workers to clean the lab, he didn't kill them, he had them deported.
Gus does not kill arbitrarily as a preventative measure when he can ensure safety in other ways. (And no, he did not kill Victor for flying too close to the sun as Walter thought, he killed Victor because he saw that witness sketch of him in the police station.)