I don't think he aided himself by pleading not guilty. He claims that he was talking to Tom Youngs instead, however if you watch it again on TV you can see him clearly looking at the ref when he says it.
I'd like to have seen Rory Best in ahead of him anyway! I hope the RFU don't bottle this by letting him DH go away with the Lions and starting the ban from the beginning of next season.
It was not clear from what I heard from my ref mic. I think Myler thought by not kicking it out on the full, i.e. bouncing it into touch, that he would get away with it. There is absolutely no excuse for what Hartley did, though. Given that the RFU entry point for a ban for abusing an official...
..should deal with abusive players!
Dylan Hartley warned once about how he was talking to the ref, and then given a straight red for calling him "a Googling cheat."