I'm going to say first off that this is kind of depressing. That said, after my initial knee-jerk reaction of "fuck you, Duolingo," it occurs to me that is might be a better outcome than them pulling out of Russia altogether.
Providing Russian citizens easy access to language learning provides them access to non-Russian media and non-Russian discourse on queer issues.
In my own experience, learning a language as an adult has taken place in ~3 stages: 1. learn from instructional material exclusively, 2. consume foreign language material with native-language support/tools, 3. learn more of the language via context. If having an app available to folks in an oppressive country helps them get through stage 1 and into 2/3, it gives them a chance to escape the hateful discourse of the regime... In theory.
On the other hand, maybe it's just capitalists being capitalists.