Given we are talking about jamming a repeater in a rather extreme orbit, you have to account for the speed of light delay. By the time a bad actor gets news that a message they don't like is being transmitted and starts up the jammer the broadcast may already be over (assuming its a data transmission that comes in bursts of packets)

That's a very good point. I suppose that, if we assume a bitrate, and we assume partial messages are irrecoverable, then this puts a limit on the "uncensorable bandwidth." But it's easy to imagine a protocol that splits large messages into very small pieces to so that each message is below that limit.

Nothing really prevents continuous jamming the whole time it's overhead for an area you care about. All a government needs to do is broadcast noise at a high power on the band(s) of interest to completely drown out dissident signals.