Compared to other Bitcoin casinos those are harsh terms yeah, but if you look at casinos that use Fiat money a lot of them have VERY similar if not WORSE wagering requirements. Casinos are almost always extremely restricting on bonus money.
There are always strict restrictions on bonuses, but this is more than that. In this case claiming bonus blocks withdrawal of your own deposit. The last deposit bonus I claimed on fiat gambling site was bet365 where they figured the way to record those amounts separately, you still had amount available for withdrawal + restricted amount (bonus).
And apart from that their T&Cs are very misleading (as per my post above).