PLO game at the local casino. Heads up between SB and BB at the river. SB seems like an amateur, and Villain in BB is a daily regular and seems to play pretty well and knows his stuff. Action goes down to the river, where SB checks, BB bets $155, SB says "$300" without actually saying raise, BB flicks a chip in and snap calls. He sees he's beaten, and then calls the floor to declare it's an illegal raise as the raise has to be at least $310. The floor is called, all the action is described and the raise is voided and $145 is refunded to BB.
Seems pretty scummy to call the raise and get a freeroll on the $145 knowing he'd only call the floor if he lost. Opinions?