Couldn't he gamble with them? Put one or two chips down at a time, keep the winnings as "clean" chips and gamble with the dirty ones until they're all gone?
Sure, I'd imagine so. However, just waltzing in and not visiting the counter for exchanging cash for chips might seem odd. Easily taken care of by bank rolling your trips with some real money and "peppering" in your stolen chips.
Except that this plan involves having hundreds of thousands of dollars in "real money", and this dude probably isn't that rich (because if he were, he probably wouldn't be risking the whole armed robbery thing).
Also, I'm just guessing what he looks like under that helmet, but I'm guessing your typical armed-robber type wouldn't fit in well at the high roller table.
Anyone who shows up and throws down anything larger than a $100 chip at a craps table is going to draw serious attention to themselves from the pit boss and the folks upstairs.
People just don't show up at a pedestrian craps table and throw down $25,000 chips, much less $1000 chips.
There were probably a very small amount of > $1,000 chips at a craps table anyway, and their only real use would be to pay out to a big winner.