......
It seems silly to me that someone would get worried about someone having flag of some other county or some sports team or whatever. But lots of people do. I think it is normally when they are insecure about the area they support and so get worried if anyone even likes anything other than what they do. That attitude seems silly to me, but in that case it is often best just to refrain. In my experience, most of the time, if people are not insecure they really don't care what flags someone flies at their house (occasionally you get super nationalist that are all excited about political borders that were placed on the globe generations ago and they get bothered even if they are not insecure - but this is a small minority, and exists in most every country to lessor and greater degrees).
The less a country cares about other flags being flown the better image that country has of itself in my opinion.