Well, that's another case. GMG sold you key with another EXISTING restriction. Restricton described above does not exist. There are keys that will be ONLY available in those countries. There are keys that will not be available in those countries, but with A LOT of other countries too; But there is no keys that will be unavailable in ONLY those countries.
So, either winner from RU/CIS countries won't have issues with this key, or winners from other countries (except of some few of them) will have issues too. For example, if this key actually has LATAM restriction, RU/CIS users will not be able to redeem it indeed, but also users from all other countries, except of LATAM countries.