A SINN Fein member states that the Union flag flying over the City hall deters nationalist people from going near the City Hall. It doesn't keep Sinn Fein away.
As for people keeping away from the vicinity where the the Union flag flies, I have lived here for more than 50 years and I have never heard of anyone boycotting the city centre because of it.
It is the flag of the United Kingdom, of which we are a part and it distinguishes us from southern Ireland, which is a foreign country. As for the Alliance Party, I don't hear Naomi Long complaining about the Union flag flying at Westminster, where she collects her salary.