If they can't enforce their decisions, they're not really making decisions. GP was implying that regulating speech meant "truth" and "lies" would depend entirely on which political party happened to be in power at the time. But we already live in a society in which speech is regulated, and that doesn't happen. Trump tried as hard as he could, but every lie he spouted was still pushed against, much to his dismay. He convinced people who already bought into the party line, but no one else was forced into accepting or spreading his point of view.
Freedom of speech still exists where debate, conflict and truth discovery can still occur. Regulating speech mediates free speech, but doesn't have to eliminate it. The marketplace of ideas can accept that some ideas are not worth keeping.