That's putting it mildly. I'd call it cowardly.
My Dad used to have a cow-calving operation on his farm. A cow really is huge (especially when pregnant...they grow out, not down) and could hurt you, if she wanted to, which, fortunately I've never witnessed. Taunting cows...who are not agressive at all, and really do not want to hurt anyone, is a seriously cruel thing, in my book, even if it is an old Spanish tradition. Not cowardly, but cruel and foolish.
A bull on the other hand, especially without some cows around, really does want to hurt you...I can understand a bit why the Spaniards mess around with them. Still, all of this seems to be a tradition of medieval and even Roman colloseum origins, and, in spite of the romance of it...should be abolished. Taunting animals at all (like our ancestors in the North used to bait and taunt bears, or bulls too...) is not fit for human beings to do, period.
Still the kid was stupid...and needs our prayers.
(see Proverbs 12:10 below...)