Quick Guard is good on anything, really. You can slap Quick Guard on Keldeo, Terrakion, Scrafty, Hitmontop, Meowstic, and Talonflame, and they will get the job done of protecting the partner and itself from Prankster abuse and priority moves. No, you don't need to be prone to priority like Terrakion to be an effective Quick Guard user. Pokemon like Terrakion appreciates Quick Guard support, so it can launch hard hits with abandon.
Speed of Quick Guard user is only relevant when you're trying to block slower Fake Outs, since those two moves share the same priority. Quick Guard users dont need to be super-fast like Talonflame to block Fake Out (with the exception of blocking Fake Out from Weavile, but now Talonflame needs to go Jolly). fireblade16 mentions how fast U-turn helps Talonflame out, but that's really insignificant when it comes to providing Quick Guard support. In fact, I would argue that having useful bulk and/or resistances is more important so you can bring out your Quick Guard user reliably to support its partner. Talonflame comes short in this department. Still, Quick Guard is one of the many other nifty utility moves that Talonflame learns, and it's certainly not a wasted moveslot if the bird is not running CB.
I hope that clears both argument, so let's stop with the quote war, thanks.