There's no specific rules about bonus abuse in their terms besides multiple accounts and breached their games, but don't you think your intention is bad? since you want to maximize your profit trough their referral bonus. You're not really advertising, but pretty much only want to get referrals from your PTC campaign.

This issues also similar with winning a jackpot only with faucet, you didn't risk anything but if you're lucky you could earn money when hit the minimum withdrawal requirement. Of course it depends on each casino handled this, some allow it and some won't allow.