Yeah. That if bitcoin did something against the law. The Government can destroy anything that against the law.
Yes in many countries governments announced that using bitcoin is against the law and suppose if you use means you have to pay a penalty. But till today no governament officially announced that they ban cryptocurrency in their country. that means they are against the blockchain technology and they don't have any control over it. once the governament lost there control then they will destroy anything it maybe bitcoin or something else.