If you ask me, naming your character Seinstein, Stalin, Lenin or freaking Jamie Lannister is silly. Both my characters are named after me. Taking some character from the book, movie or video game is lack of creativity imho. However, I do approve when people choose some less known heroes, but every time when I see characters from flavor of the month TV show running around the battlefield I do this ->
Another reason why people perceive Stalin as okay name to use and Seinstein as forbidden is the fact that Germans and Austrian denounced Seinstein, while Russians didn't do the same with Stalin.