As to you overall point: are Hook’s crimes on the same level? Objectively, no. But a lot of that is also because we don’t know the full extent of his crimes. We know that he did something to “Rufio” and that he was doing “Pan’s dirty work” but outside of allusions, we don’t know what those are. It’s only speculation and we will most likely not get into it, in universe.
I don’t blame Hook for keeping his ship and saying no to Ariel, I actually supported his decision. I thought Ariel was being a little unreasonable to expect him to give up everything to help her find Eric when a) that was the first time they met and b) Eric was fine and Ariel was able to find him anyway without Hook’s help. Hook obviously felt guilty about that and he apologised sincerely to “Ariel” but really, he did what any reasonable person would do which is not risk everything on a small chance. Ariel seemed to expect Hook to be like Snow and drop everything to help her.
As for what was the “dirty work” Hook did for Pan, I think Hook may have drowned Tigerlily and killed Rufio on Pan’s orders.
All magic comes with a price!
Keeper of Felix