Im not quite sure how to respond to Taylor, when one mod says don't talk bout unbaning / banning, and then another mod proposes an idea unbanning Excadrill and other suspects I am unsure what to do lol. With this in mind, I won't really respond to your proposal Taylor, however, I do want your proposal (if im allowed) to factor in "whats changed" since 'X pokemon' was banned. For example, Excadrill really only got Tech Loom as a new Revenge Killer (according to your post), and gained Iron Head which means that it has an even easier time against Gliscor.
While its true that Skarmory is a decent counter, according to the Honko Calc, +2 RS has a 22% chance to 2KO after SR, which means that mathmatically, on occasion just a single flinch will end you. Even if Rock Slide failed to flinch, what exactly are you doing back? You can WW it out but its hardly a proper solution, when Excadrill weakened you enough to try for a sweep R2, and if you Roost stall to burn out LO, then the odds only increase that you get flinched, or hit with a Critical Hit, or so on.
With all that said, I don't actually want to fully argue all this, I just want to make the point that personally, if I wanted to be open about allowing previous ubers into OU, I kinda want to know what makes them less "broken" than they were deemed before.
I will let you make your argument first tho, my apologies if I derailed.
EDIT
Just realised I just came off as kinda elitist, might go back and edit to change the tone lol. Sorry.