I'm not sure that's necessarily the case. This case doesn't seem particularly good for assumption of risk to me. Usually, the doctrine applies to things like horseback riding, skiing, swimming, sky diving, etc. where there is a public policy preference to permit people to engage in the activity in question, and a recognition by the courts that if you don't permit assumption of risk, the business that caters to that activity will simply shut its doors. It also usually deals with a situation where the parties involved understand the risk.
But in my view, this case really isn't the kind of case where a court is going to say, "Sure, we want to facilitate this kind of activity."
Someone posted that they wondered how pie eating contests or hotdog eating contests would react to this. Maybe if you're a judge, that thought process would prompt you to uphold the assumption of risk clause in this case, but I don't think they are just going to read the release and make sure that they used the magic words "assumes the risk." My guess is that they will be looking for ways to throw it out.
Then again, I'm a defense attorney, so my bias is probably showing....