It's really hard to say because Parliament wields extraordinary powers. It once found the Government itself in contempt, triggering an election; IIRC, the only time that's ever been done was in Canada.

In the few other times contempt charges have been laid no punishment was applied, at the discretion of Parliament, or Parliament dissolved before any punishments were prescribed.

What's really fun to consider is that Parliament could apply criminal charges upon Zuck, and the USA may have to arrest and extradite him.