When a restaurant which you've been going to for years one day decides to serve you your favorite meal with a bit of poop on the side, do you not have the right to be upset about it? They're not under any obligation to serve you meals you're happy with. That has got to be the most fallacious analogy I've seen in a long time, and that's ignoring the fact that serving poop would get you in serious trouble in most jurisdictions. "False equivalence" barely covers it.
There is a basic social contract of not being an asshole to users of your product
Nope, nope...you win. Even more fallacious. Being an asshole to your users is a meme in OSS it's so common. Someone should tell that Linus guy about this 'social contract' he agreed to and signed that he's in violation of. /s
Claiming you support this philosophy, while acting against it, is hypocritical, and abusive towards people who do believe in it.
You think there's a philosophy. Some other people here do. There is no consistent OSS philosophy. There wasn't back when Stallman was thinking "what should I call this thing that is Not Unix" and there isn't today. If that was remotely true we'd still be happily using GPLv2. Because at the end of the day there is what is written in the license, and then there is wishful thinking. Sometimes wishful thinking results in nice things, and sometimes...well...here we are.
If you want to place restrictions on how your software is used and who gets to enjoy it, that's fine, but make those terms explicit by choosing the appropriate license and business model from the start.
Ignoring the laugh-out-loud silliness of "you should pick all these things about your startup day #1 and NEVER CHANGE THEM", exactly what terms of their OSS license did they violate? Be explicit. Don't wave your hand and say "but social contract that doesn't exist!", "but philosophy I made up and want to apply to people who didn't agree to it!". Because a license only means what's written down in it, not what we want it to mean. I get that you think there should be a "No assholes, we'll never, ever pivot to meet market changes and we pinky swear we won't rug pull on you" license that people should be forced to use, but I don't think to many people will sign up for it. See: GPLv2.