Potential bug with Kayle ult

I've been playing kayle and i've noticed i can keep attacking while stunned, as long as my ult is on(and e). If anyone can take the time to better test it, go ahead xd. I first noticed this with TF's gold card.

Update: So i tested it out with a TF who has gold card maxed out. I get to get an auto through, on mid duration of the stun. I shouldn't be able to do anything during that point but kayle manages to auto. ULT NOT REQUIRED.