I do not see why plugging these folks back to the common sense grid would hurt. If folks want to normalize the region, why not starting by awarding them this privilege. If there is one thing that proud people do well, that is hospitality.
....and that's the easy part, cos that threat is localized to that stadium. What do you do with the safety of tens of thousands of fans on a daily basis? ...prevent kidnappings e.t.c?
Meh we are speaking about 2018...as for now, the stadium has at least 30 000 folks every two weeks. Seems good enough for terror attacks? Tourists, I saw no problem when people went to RSA for a whole month, why would it be different for those two measly games Grozniy would have.
Or is there something I do not understand? Aside from that, yeah maybe you are right, the best way is to be safe than sorry.