I think you are correct
If the person was born in the US in English-speaking family then he might have troubles distinguish between some accents, including Russian.
I've been mistaken for: British (WTF???), German, Polish
Russian accent is close to: Polish, Bulgarian, Romanian, Moldavian (probably other countries from Eastern Europe) and some accents from Middle East
But only Eastern European can spot one another by accent almost w/o mistake![]()