Why? And i'm genuinely asking because to me it wouldn't be different. Either way the shirt seems rude to me, whether the parent chooses it for their child (why would you do that?) or the kid chooses it....Why does this child want/need to say "bite me" if they are meaning it in a rude way. I can understand if she is just naïve and thinks of only the cute vampire play on words but other people are not all going to read it that way and there in lies the problem for me.
I was a very naïve 13 year old(who turned into a very jaded 15 year old quite quickly) and I wouldn't have understood fully if someone made a lewd response to a "bite me" shirt at that age.
The fact is, I don't find the shirt rude in the first place. T-shirts are a widely used form of self expression so I wouldn't put the words in my child's mouth, so to speak, by picking out expressive t-shirts. But I find it acceptable for an older child or teenager to pick out clothes that express themselves if they aren't racist, sexist, or otherwise bigoted/hateful. I'm not going to get worked up about a bit of teenage style attitude t-shirts. They are much less offensive, IMO, than all the "girls rule and boys drool" style shirts that made for much younger kids, or the "sorry girls, I only date models" on young boys.