Because they always have had the legal right to do as they please with their platform.

This protest isn't by the workers - it's by unpaid volunteers and there is no law saying they have to listen to unpaid volunteers - and while we can organise there's no - "unionization" persay - they aren't paying us. So yes, they can and will bust through up the picket line, holding as many people hostage to their platform despite the moral standing of doing so.

Sure people don't like that, and therefore they have no moral right. But business when they get greedy generally don't care about moral rights, and will do everything on the correct side of the law to keep their power and userbase, and considering how eroded the antitrust and anticonsumer laws are right now, reddit has a lot of ability to do shit they shouldn't really be allowed to do.

Even if legal suits do happen as a result of this, it will be a long drawn out process where Reddit will either Win, or declare bankruptcy. Then you can bet a large multinational tech company will buy it out. Google and Microsoft have been wanting to get into social media for some time now, and meta is still looking for a hot new thing it can hedge it's bets and get more userbase - to the eyes of these companies the data and software Reddit possesses has inherent value even as the dwindling userbase, especially because Reddit aren't really deleting data from old accounts. Hell current data would be a great data set to train AIs on and therefore big AI companies would love the opportunity to own said data. I could totally see a company buy it up, shut it down and then use the data to their own ends.

Also taking down the servers, while I completely agree with that in this case - and if 4chan were on board it probably would've happened - though I doubt it could be sustained long term, maybe a few months at absolute best, a few hours at worst. Doing so via the means we have available does present a legal concern not many are willing to cross, especially considering the implications of getting caught, most people are into peaceful protests, for this sort of thing not ouright trying to wreck shit - going to prison over a gripe with a social media site seems like a really dumb thing to ruin your life for.