The show’s handling of Karofsky forcing a kiss on Kurt wasn’t the best it could be. Since Kurt chose to keep the kiss a secret (from everyone but another kid his age), it is impossible for parents and teachers to intervene and show the assault up for what it was. And given that both Kurt and Blaine are gay, it is understandable that they feel some kind of twisted allegiance to the closeted boy. It’s hard not to feel bad for him if you’ve been closeted and confused yourself. However, most of us don’t threaten the lives of our secret crushes.
But the fandom shows how the story failed to interpret the event appropriately. Not only is the event refered to as Kurt’s first kiss, but there are fans out there who “ship” Kurt and his tormentor.
Because the show made it reasonably clear that the reason behind Karofsky’s bully behaviour was an attraction to openly gay Kurt and because the nature of the assault was never actually addressed in the show (Blaine could have done that when Kurt spoke about the kiss “counting”), fans (especially younger ones, from what I can tell) have romanticised the assault.
As far as they’re concerned, a boy can shove you into lockers and make your life a torment and forcibly kiss you, as long as he does it because he’s got a crush on you. If I had a pre-teen daughter watching that show, I’d certainly be sitting down with her to talk about what is and is not an appropriate expression of attraction. Violence, intimidation and assault do not make the list.