> What would be your opinion of US president, if he goes to to retire in Russia?

Did Gorbachev retire outside Russia? I wasn't aware of this. He died in Moscow. The last time I heard about him before this was when he attended an RT event in Moscow (which was also attended by Jill Stein and Michael Flynn). Where outside Russia did he retire? Why did he leave this place to die in a Russian hospital? Your comment leads one to infer he retired to the US.

> I'm reading some Russian news site, and almost universally Gorbachev is hated by Russians.

Russian news sites are notable lately for not allowing the free expression of Russian opinions, so what they show you may not be representative. I'm not saying you're wrong but that Russian news sites aren't great evidence that you're right.