I dunno, a few examples being made from protestors that are clearly not part of the mainstream UAV community might not be all that much of a bad thing. Note also that the UK media (which hasn't exactly been overly opposed to Extinction Rebellion) is even distancing this group from ER by referring to them as a "splinter group", so they're even protecting ER from the inevitable backlash if this goes ahead.
If nothing else, it'll firmly establish in the minds of the rogue elements that *are* within our community what they'd potentially be facing if caught, especially if they get hit with a civil suit from Heathrow. If that makes even a few more pilots pay a little more attention to flying safely and legally, then that's a win for all concerned, right?