It seems pretty black and white, really. It's private property. They've paid for the privilege to live behind a gate. They've put up signs that request people not trespass. The signs have gone ignored. They've had additional signs put up that specify a group they'd like to respect their privacy and not trespass. I don't blame for being upset. Where is the line drawn? If a group of cyclists are coming down and they're low on water, why not use one of the residents' hose, sink, fridge? If people used my property for a shortcut, I'd be ticked too. You as an individual may be a well behaved stop at all stop signs kind of cyclist, but I am guessing they also get the cyclists that rip through THEIR neighborhood ignoring all rules of the road. I imagine that is what has led to their issue more than the occasional nice cyclist. One bag egg spoils the bunch.
At the same time, I am a cyclist and understand that it also sucks riding on sketchy roads. As a result, I avoid the sketchy roads if I'm out solo. It seems more that an effort needs to be taken to bring up the lack of safety of the roads to the County folks and have that addressed. Alternatively, in an area as affluent as Diablo, I imagine that there are a few cyclists that live behind the gates that you may be able to befriend and plead a case to get some kind of rule change.