The point is, that Fortune Legends should react proactively if "responsible gambling" is important to FL. EM provides the information about SE to the customers of FL. This means, that FL can (theoretically) also receive this kind of informations. This is also what they write in their data protection regulations.
FL has a clearly stated SE procedure. They, like many other casinos, are free to do so and are perfectly within their rights to expect their customers to follow the procedures accordingly. If those procedures are at fault then by all means they deserve a critical going-over. Otherwise they stand and should be respected.
What the casino does above and beyond that is up to them but expecting the casino to chase down info on players __outside__ of the player's activity at their casino is pretty suspect. Also, it's quite easy to fall afoul of the GDPR rules doing so. All in all it's likely not nearly as trivial an effort as you seem to think.