For the record, I agree with you that those guys that scalloped up the side of a cat walk to catch some air are idiots and a**h****. However, that does not stop their lawyer from arguing that their client is in the right.
As someone who treats the edges of catwalks as a terrain park at times, the idea that you must only go straight down a catwalk bothers me. I understand that the intended use of a catwalk is to get you from point A to point B, but the point of any ski trail is to do the same. Just because some choose to have their fun using the terrain in a different way doesn't make them totally in the wrong. IMHO, it's no one persons choice to decide how others get to ski a mountain. If an area needs explicit controls on what is/is not allowable, it is the mountain operators responsibility to make those rules clear and well signed.
That said, what is appropriate skiing depends not only on the terrain (catwalk in this case), but how busy it is. Just like it would be inappropriate to arc GS turns down a busy merge point on a green trail Saturday at 11:15am, cutting people off on catwalks during busy times is inappropriate.
The last time I was at Squaw a young woman came flying down Emigrant face and across the catwalk (popular way for people to get to Shirley runs). There is a warning sign there, but I think she was going too fast to see it, and too out of control to react anyway. She did not land gracefully after getting air off the catwalk.
I don't know why it bothers me but where did the idea that a cat track is called a cat walk? This is a cat walk:
This is a cat walk:
This is a CAT TRACK: