I don't support a Skarmory ban, but I do support discussing this type of stuff when it comes up.
If these things are as non-sensical as people are claiming it shouldn't be hard to write a well-reasoned post that doesn't just call someone "dumb", "stupid", "idiotic", etc. People can like that post if they agree with it and we can move on.
A couple people responded with good points above. In some senses I'm just collating those in to one post here.
Before I do that, I want to get at some of the things that have been brought up so far concerning the tiering philosophy:
We don't tier with any particular type in mind.
We don't tier to "keep the good types good".
We don't tier to make all types equal.
We tier so that the metagame is balanced, isn't excessively reliant on team matchup (obviously there are limitations on this given the nature of Monotype), and has enough diversity for us to enjoy playing it.
A central element of the tiering philosophy is "Does it add to or subtract from the metagame?".
When thinking about "swapping" the Aegislash ban for a Skarmory ban, I think we're losing far more than we gain. This centers around 3 things:
1. Adding Aegislash to Ghost teams still leaves it among the lower tier types
No one is going to argue that Ghost is not better with Aegislash. I'm also not going to claim to be an expert on building/playing Ghost. However, through the entire ORAS metagame we never really saw Ghost have widespread success with Aegislash. There were particular players that excelled with it, but it has always been among the lower tier types and not particularly impactful on the overall metagame. (just my opinion, not a statement of fact)
2. Removing Skarmory from Flying doesn't ruin the type, but does require everyone to significantly change their approach
Obviously Skarmory is important to Flying, but I don't think it will completely ruin the type if it was removed. There are just far too many good Flying types for that to happen. Lando-T can certainly fill the role of Rock-neutrality, SR setter, and defensive "wall". It doesn't have the staying power of Skarmory, but it is a much better replacement than Bronzong on Steel teams. If anything, I think it might increase the diversity of Flying teams (a good thing). It could also allow us to consider unbanning CharX or Mega-Alt, which is very interesting in my opinion.
3. Adding Aegislash while removing Skarmory decimates Steel teams.
On Steel, Skarmory is the all important immunity that many Monotype teams need to be successful. Importantly, it is one of the only Steel types that has significant staying power throughout a match. Both Misaka and Arifeen pointed out that shifting this role over to Bronzong leaves the balanced Steel teams very weak. Also, removing Skarmory cripples the offensive builds that are very common right now by removing their primary hazard setter. This alone isn't necessarily a bad thing, but adding Aegislash has to bring something that fills the void and makes the overall metagame better.
Adding Aegislash to a Skarmory-less Steel team doesn't do much... The immunity core doesn't exist. Those balanced Steel teams that we often cite as being too powerful with Aegislash aren't an option. You get a more potent Fighting immunity for balanced builds. Offensive builds get a better version of SD Doublade. Both playstyles are overly weak to Ground attacks. Aegislash also comes with the annoying 50/50s from King's Shield, which I don't think anyone truly enjoys or finds healthy.
Overall, what did we accomplish?
We slightly improved Ghost, which we know has minimal impact on the overall meta. We nerfed Flying and forced Flying trainers to explore new builds that don't feature Skarmory. Finally, we killed off an entire playstyle (Balanced Steel) and made the offensive Steel teams worse.
I don't see how anyone can interpret this as improving the metagame.