I don't think Sony is overreacting too badly, I meam would you want to see the system you spent years working on trying to perfect be torn apart by a single man in a few weeks? I would be pretty upset too.
Yes, Sony should've set their defensive standards higher, but still, they should be allowed to ban people, it is their system.
They certainly have the funding to do whatever the hell they want, they make other electronics beside ps3s, including Tvs and other junk, all which increases the bank they make.
I'm sure if I was actually banned from Ps3, I would have a greatly different opinion on the whole matter, but I'm not banned, so this is the opinion I have.