You don't now what the Swiss have. You don't know how important the sealed information is. The Swiss waited 10 months. If they didn't want to extradite, they could've released him sooner. If the US really wanted him, they would've submitted the request years sooner since they knew he visited Switzerland and has a place there. If the US really wanted him, I'm sure someone somewhere would've gotten the information the Swiss wanted.
ETA I am not defending Polanski. I think he is a reprobate, but from what I've read (here) about the legal details of the case, it sounds like some very sketchy things went down. I'm defending the judicial system, as flawed as it is. Others have expressed this better.