It’s a tad obscure but the joke is basically this:
PragerU (if you’ve ever seen their content) tends to reels you in with generally agreeable and sensible stuff like freedom of speech, but stay and listen awhile and Prager will hit you with blowhard nonsense like the bottom right panel.
Some internet platforms have taken a position that they are not going to sponsor extremist content that contradicts science and could get people killed (diehard opposition to lockdowns could perhaps fall in that range). However, truth be told there’s always a place somewhere on the internet for people with views like Prager.
They just don’t necessarily have the right to spread their gospel *anywhere and everywhere* on the internet, because platforms have their own free speech rights, too.