You could perform a DDOS, though that's illegal in both the US and EU.

Worth a try, but probably unsuccessful: Try and do a password reset with Namecheap in an effort to gain control of the domain. You have the credentials to back up what the site purports to be. Call frequently, because Namecheap would probably not want to handle something this hot if they knew it was this hot.

Make a (disingenuous) high offer to buy the domain through the filter on the whois. That'll give you a point of contact if nothing else.