Re: "care about having food to eat"
Yes, like my granny used to say; "You can't eat principles".
Not that I don't have principles, but if I'm going to become a martyr for a cause, it'll have to be for something a bit more significant than Facebook. For everything else, the "live to fight another day" approach seems far more sensible.
As for constructive dismissal, I'm fairly certain that if I told ACAS I quit because "I don't like Facebook", they'd laugh me out off their offices, and I'd still end up destitute (and probably unemployable). They'd be wrong, of course, but then explaining the significance of this to technophobic dinosaurs is about as futile as explaining why email replies should be underneath the message they're replying to, not on top.
You just get the "dead stare". It's pointless. Not only would I martyring myself for something ridiculous, and not only would nobody give a damn about my sacrifice, but none of them would even have the slightest clue why I did it.