Provably fair casinos would go bankrupt if they would offer a bonus without some sort of exorbitant rollover requirement. Reason so, they are FAIR which is the keyword here. Companies that offer 200% cash bonuses for casino games clearly run a rigged house and should be avoided. Just take a look at the threads here this week, it's pretty clear who offers honest games and who does not.
I am sorry but I am not sure I understand your logic here quite well. Bonuses and free spins have been one of the biggest standard promotions in classic gambling industry. Why exactly you believe that in provable casinos it is different? Because all the big slot producers (NETENT, IGT, PT, WMS) are rigged?
You can't find logic somewhere, where there isn't any. Alan was just trying to look smart in front of the newbies so he can lure them to his site... and they can lose their money in the provably fair casinos that pay him.