Yes the issue is Netflix's liability. The reason it can be de-anomized is because people reveal more info in some other database (for example idbm) - if people willingly reveal more info in some other db, is that netflix's fault?
As stated elsewhere Netflix should just have a clear opt-in for sharing the data and we can continue on.
I don't think this helps them much in court of public opinion, and it helps even less in not pissing off a segment of their customers. Making it opt-in seems like an easy compromise. The only downside I see is if they get a really low response rate.