Oh man! That is escalating to some new highs...lol. Clearly casino is at the fault as far as I can tell for below mentioned reasons:

1) Booking his action, (If he/she made so called multi accounts, though even with four account and with 10k sat bonus math does not add up).
2) OP posted a screenshot of his winning against some guy named Pauli (Which is not mentioned by casino in multi accounting list), so assuming screenshot is not fake, Technically they cheated both Pauli and OP.
3) No fair casino will post IP addresses with username publicly.
4)They can up with such excuses in future for sure if they are going to that extent for couple of bucks.