Can Russian citizens apply for an EU medical certificate issued in accordance with Regulation (EU) No 1178/2011?
Yes, provided that the purpose of the medical certificate is to operate a non-Russian aircraft, i.e. if the person is e.g. destined to fly as an employee on an EU airline. If the intention is to fly in Russia or Russian registered aircraft, then the person cannot be issued with an EU medical certificate as that would be support to the use of banned aircraft or operators and hence prohibited. For private pilots (who presumably would be flying themselves and are Russian citizens) no EU medical certificate should be issued.