I have read a lot about Navalny’s views on immigration, and I accept that they are unpleasant and not acceptable.
However, we should remember that Russian society is very, very different to European and US society, and their cultural beliefs are different. Therefore, Navalny’s views will be different to ours, and we might not ever be able to accept or agree with them.
Also, it’s important to understand that Navalny was a political figure who eventually hoped to get Russian people’s votes and to win elections. To do this, of course he’d have to appeal to people, and presumably lots of these people share these views he mentions - even though we don’t like those views and we find them unacceptable.
I’m not at all trying to justify or defend his views by saying this. I’m just pointing out that some of (if not many of) the people whose votes he would want to get as an aspiring political candidate would have these views and he would want to be able to connect with them.