Floor Ruling on a player's action

[thenutz9]

In a heads up pot, guy 1 checks the river. Guy 2 pauses then stacks all his chips up and slides them forward past his cards. They move past the cards and are still in his hand, and Guy 1 instantly calls. So guy 2 still has his hands on the chips and pulls them back, then says I check. They call the floor over for a decision. What should it be?

There is no betting line at this casino.