If they still want to move on with their change, they can fork themselves off the network, but 'til there. Authorities hold no more power in this place. What "should" or "should not" happen is down to users to decide.
Its just more scaremongering. They have been trying to scare the people to do with their Bitcoin as the regulators wish ever since Bitcoin was invented. They have never succeeded and never will. But they continue, trying as hard as they can to disrupt Bitcoin is some way. Their scaremongering methods are becoming more and more grand, now even going as far as involving the G20. However the scaremongering remains inefficient.
They will never succeed. They will fail, their banker criminal friends will fail and Bitcoin will stand.