Because their customers/voters want it? Me, I very much prefer censored HN to free speech 4chan. The question is, what are you doing here if you prefer 4chan where the "truth" is not censored?
When you ask, "How should governments fight disinformation," what you're really asking is, "How can governments deny their citizens the right to choose what information they read, watch or listen to." When it's phrased like that, it's not so appealing, is it?
that means no. Do you want to remove _every_ moderation made by companies/governments in all online forums, including HN?
I support private forums being able to moderate. I oppose governments having that same power.