can they legally seize your funds should you refuse?
no but you wont be able to use there services... if your that against it you could try sending them a message to get them to send bitcoins to your bitcoin address. if your American you pretty much stuffed as America and alot of its users from there have been nothing but a pain in tje ass for gox so thanks to the US government and a few people gox has to do all this crap to protect itself
as for me im from the UK so have very little trouble funding and withdrawing from gox