Be careful, this is against their rules. Similar to Bovada, they don't enforce it but they may some day.
You're right. There it is:
16. If you do not break a deposit on which you received a bonus into at least three relatively equal wagers, the bonus and any winnings can be rescinded.
Of course there's this one too, which they break themselves quite often:
1. Bonuses will only be awarded to account holders who provide a verified name, street address and phone number. All bonuses are in the form of cash unless otherwise specified. Bonuses does not apply to Person to Person deposits, a 5x rollover applies and the
maximum bonus amount is $500.