Allin players cards get mucked

[CWilly]

An interesting hand took place at my local casino last week. We were down to 5 and ON THE BUBBLE(!!!) and a guy pushes allin over the top of the pre flop raiser. The PFR is deliberating calling but the allin player thinks that he's folded and throws his cards towards the muck (but they are not actually lost in the muck). The floor rules that the PFR gets to double up off the allin player even though he hadnt actually called the allin, leaving allin guy with 300 chips! Needless to say, he wasnt very impressed and busted soon after. Such a sick way to bust on the bubble as he had quite a decent stack!

Is this ruling standard?