I like HIAs response.
Chances are if that had happened to me I would have said something myself. If it was me that was getting uncomfortable I'd say something. Or I would have moved my chair so my back was to them.
Oh and for future reference, asking to move tables can be a pain in the arse manoeuvre. If you feel inclined to ask to move, start by asking your waiter to ask the other table to not be so rude.
Regards, a friendly waitress. :p
'People are never perfect but love can be. People waste time looking for the perfect lover rather than creating the perfect love' - Princess Leigh-Cheri from Still Life With Woodpecker.