We can do it. It's just data. Of course long waves carry very scarce amounts of traffic. DVB-T or even better approach would be using satellite. There are digital satellite technologies like DVB-S which could carry that kind of data. It's only a financial issue.

It just moves the thing that gets censored from the website itself to the equipment needed to receive it.

Which is infinitely harder for authorities to control.

How wikipedia is different from any other website useful for victims of police state?

It's an encyclopedia of everything.