Hurdling suggests feet first, or, more precisely, foot first. Full speed down the line with a steel-cleated foot attempting to go over the catcher who, incidentally, may not have been properly taught to keep his helmet on...
This is a no-brainer guys. It may not be specifically addressed in the rule book, but how about applying some common sense and judgement.
If I'm behind the plate, the runner is out and ejected, and the coach can protest all he wants.