Medvedev plays for himself, not Russia, other than in the Davis Cup. Neither Barty nor Medvedev had their national anthems played during presentations at the Aus Open. As long as he refuses to be drawn into comment on the war in Ukraine, he should be fine. But if he starts wearing clothing with a "Z" on it (as a male gymnast did when accepting the Bronze Medal while a Ukranian stood on top of the podium), the proverbial will hit the fan.
Remember also that the players dominate how tennis is administered. Djokovic wasn't brought undone by the organisers of the Australian, Indian Wells or Miami tournaments: they were all doing everything they could to get him to play. He was banned by the Australian Govt and the CDC. Medvedev won't be shaking in his boots over the prospect of the ATP disciplining him. After all, the ATP couldn't even bring itself to ban Zverev for whacking his racquet repeatedly against the umpires chair near the umpire's feet recently. But if Medvedev decides to provoke outrage, that's when tournaments might withdraw invitations or governments might refuse him visas on character grounds.
Remember also that the players dominate how tennis is administered. Djokovic wasn't brought undone by the organisers of the Australian, Indian Wells or Miami tournaments: they were all doing everything they could to get him to play. He was banned by the Australian Govt and the CDC. Medvedev won't be shaking in his boots over the prospect of the ATP disciplining him. After all, the ATP couldn't even bring itself to ban Zverev for whacking his racquet repeatedly against the umpires chair near the umpire's feet recently. But if Medvedev decides to provoke outrage, that's when tournaments might withdraw invitations or governments might refuse him visas on character grounds.