i have, on rare occasions, done a 'tele' turn or two with my heels unlocked, because i was in touring mode and needed to go down a small slope. in those cases snow conditions or the terrain may have made it a little easier to do it that way. i seem to recall it's easier than doing say an alpine jump turn with your heels unlocked. it's not a great way to ski by any means and has a high head plant potential.
as far as the guy you saw there's nothing i wouldn't do a few times in the name of screwing around, or maybe iain needs a whole new population to get all about.