Personally, I'd prefer such comments not to be made in a euphemistic way and just speak plainly. If you have concerns (valid or not) with immigrants not following the native culture and social norms then say that.
Many of mine were also flagged, despite me being extremely polite.
You really have no choice but to phrase yourself in a way that's only recognizable to the in-crowd. Even here, with the polite expression, he is catching flak.
Personally, I don't discuss politics in real life anymore. Risks are too great. Just the Internet, where on some forums (not this one), you can be honest about what you think.