That's only logical as there are few COD PC players to start with. The scene is simply smaller. But I would like to see what would happen if a mixed competition was organised.
They did this sort of stuff before and pro players on gamepad can't even handle average players on mouse and keyboard. Don't know if autoaim was enabled or not. It only makes sense and doesn't prove anything really, FPS on console and PC is a totally different beast.
There was an FPS game called shadowrun or someshit where it had PC and console players.. however the game was designed to have certain limitations for each side to make it more "balanced" between the systems so essentially they were playing two different versions (consoles had sticky aim/aim assist, PC had movement penalties, higher recoil, etc) so the results were completely fucked--in fact the console players dominated at first due to the PC version being nerfed to shit.
It's more about the form factor between controller and mouse/keyboard as opposed to straight up "herpderp console v PC." It's just a fact that you don't have as much per-pixel control with a single thumb and a joystick then you do with your entire hand and a mouse. Most PC games out there are compatible with controllers anyway, use one in any FPS without sticky aim and you'll get wrecked.
IMO competitive, skill-based FPS died with DoD 1.3 and CS 1.6 when CAL dropped. After that, all the old Quake-style of FPS were completely replaced with arcade clusterfuck shooters. Don't get me wrong, CoD/BF are still fun for what they are but the mechanics do not lend themselves at all to pure, skill-based play.