a decline in grammar and written English was partly linked to the text massaging craze.Duh. But really, it's the other way around, and only in that format. The text massaging craze leads to a decline in written english in that media transmission format due to the fact that the text entry interface, and the medium of reading it, is not conducive to prosaic dissertations. Paper written essays are not the place for l33tsp34k. Teach your students that.
The student was communicating effectively, but for a given media transmission format, and should be taught where that's appropriate. I'd give the kid a failing grade for being cheeky and for not effectively communicating (which is the point of excersize). Then I'd get right back to sending all of my IMs in lower case and sans punctuation. L4m3r.