Gaelio has done almost nothing in this series except follow the law and sincerely fight for what he believes to be right. I don't think the guy has done anything shadier than hide his identity.
Rustal also didn't allow to Iok to use Dainsleif - that was entirely on Iok's initiative. Rustal covered for the guy after the fact and clear the matter up with McMurdo, which included removing the remaining turbines from Gjallarhorn's most wanted list.
Rustal is not a pure guy or anything, and says as much in the most recent episode when Julietta talks about how she was lucky to have adults around her that she could trust. He has done some shady stuff. But like between him and McGillis 'yep gonna marry a kid and take over the entire universe' Fareed, I'm not going to pick the guy who wants to install himself as emperor of space.
And beyond being somewhat shady in his methods of preserving order, there's the fact that Rustal preserves the current order, which includes the structural inequality the series is themed around. He's very much a villain and we shouldn't forget that. But he's such a good villain and his motivation is reasoned out and believable so, you know.