Whilst I disagree with the protestors arguments vis-a-vis drones, I'm not sure their lenient sentencing nor the judges comments will send the message that it's open season on UK military installations.
As demonstrated by the link I posted earlier about the Fairford B-52 protesters, and the Indonesian Hawk protesters before them (
pounds 1.5m Hawk attack women freed - News - The Independent ), direct action of this sort has always been something of a British tradition (as has the subsequent lenient sentencing).
It didn't open the flood gates then, and I don't suppose it will now.