That's not how it generally works when you get politically motivated emigration. They move to your country while taking their politics with them, and then insist that you adopt their political agenda as part of your foreign policy as well. This sometimes goes on for generations.While it is natural for someone in his position to want to continue the fight from abroad, I think the deal for most Hong Kong people will be that they move here and integrate.
With people who move in order live a better lifestyle, this is less of a problem. People with a "cause" are another matter altogether.