I don't agree with you about that sentiment. Navalny compared middle asian immigrants to "cockroaches" and "rotten tooth". Just because Navaly is anti-Putinist doesn't allow him to say such disgusting things.
Navalny is not angel and I do have many questions for him, yet, I feel you are mostly reading propaganda websites.
About migrants compared to rotten tooth - from his official youtube - https://www.youtube.com/watch?v=ICoc2VmGdfw