A brilliant Tweet!
And just in time to induce total freak out on the Sunday shows.
If we accept the premise that the people of the US are engaged in a (cold) civil war against the deep state and its various supporters, then it's critical to identify the respective combatants.
Since the Mockingbird media is in actuality simply an extension of the deep state - and vice versa - then so too do they represent an existential threat to national security and our constitutional republic.
Under that scenario, the 1A no longer applies, since we do not give aid and comfort to the enemy. See Tokyo Rose or Lord Haw Haw during WWII. So, what Trump is doing is setting up the premise that the enemy propaganda organs should not be afforded 1A protection.
You can imagine the reaction if this attempt was made too early. It's a slow process, but one that is critical to the success of the patriot war effort.