No one expects Russia to accept any foreign rulings. However as the Nuremberg trials proved, acceptance can be enforced by the stronger party. And in the likely case this doesn't happen, the court ruling can mean a lot less foreign diplomacy leeway for the US government when it comes to dealing with Russia. Also a US ruling would extend to every country that has extradition treaties with the US. So anyone proven guilty would effectively be a fugitive in a third and the most powerful and influential third of the world. Look at what the international criminal courts ruling already caused. Putin didn't attend the meeting of the BRICS+ countries in South-Africa. The same would go for Brazil who also accept den-Haag.

Even if the leadership of a country would like for any proven criminal to appear in their country and would like the justice department to not move, in any and every democratic country, they couldn't without causing a major breach of constitution.

Anyhow, trials like these must, without fault, be spotless examples of correct rulings, for there to be any resemblance of unpolitical justice