Perhaps they want to show that they are keeping the ROC in mind, and he is happy to see them do so. As for next year, it's up to the Hong Kong compatriots 'groups themselves. As for whether they can put up ROC flags, that will depend on the law. Like all overseas agencies of any government, ROC agencies in Hong Kong will respect local law and local customs.
明年會如何，還是要看僑團怎麼辦，能不能掛國旗，那得看法律規定，中華民國在港機構，就像任何駐外單位一樣，要遵守當地的法律，尊重當地的風俗。