@Spector_Otterquill, while, I already made my opinion on it clear. Something else stands as well:
People aren't perfect.
No matter what we say or do, people are always going to make, cause, be, mistakes. On purposely or not, it's better to help them in their failings rather than rave over ONE instance or post in this case.
Anyways, it's good that you'd trying to uphold the rules, but don't take it too far by criticizing people over one or two posts. Some people have been typing and talking like that their whole lives (in texting I suppose haha), and I don't think that anyone can just STOP overnight or in a second. Basically, what I'm saying is that you should just give them one quick warning and leave the situation altogether.
You'll be much more successful that way. However, if they start to ON PURPOSELY try to annoy and disobey you solely to "get back", that's when you can get help or try to clear things up more. Other than that, there's really no reason or point trying to force people to NOT talk the way they do.