I actually did think about that the other day, prompted by my getting some ATC freq disruption over the alps due to a rogue transmission.
If they do try that, or any other of the stuff they are threatening, such as attacking crews and groundstaff then I hope "Conspiracy to commit a terrosit act" or similar is thrown at these people and they go away for a long long long time. - what they are planning is a terrorist act, not a demo.
I just wish that the BBC et al would stop condoning their message. Every news item finishes with the (incorrect) statements about about how much damage aviation does to the environment. Its a discussion that probably should be had, but by tacking it on to all the news stories about these criminals, then it appears to condone their actions.
Out of interest, if say the tower frequency was disrupted: you're on final, cleared for the ILS, handed to tower, tower is disrupted and you can't get clearance to land. VMC, runway is clear (or you can see one departing, or one vacation) - what would you say was the safest option? Land anyway - vacate and get onto ground freq? or go back to 'director' or 'radar' and execute a standard missed approach? bother with Sqwawk 7600? or not?
I would suggest that I would probably continue to CAT1 minimum, keep trying to get the tower, get director on box 2 and ask what to do? I know that this is an unlikely scenario, but it pays to think this stuff through ahead of time.