Because this sort of thing should inform the expectations that customer holds of the business, of what they can entrust the business with and what better to take elsewhere, how to expect them to act now and in the future. Like, businesses are not actually black boxes in the same way that not all actors in any realistic marketplace ever have perfect knowledge. Useful abstractions, but only up to a point. You got any inside-ish info? Use it to your advantage if you can.

If you know they are subject to that kind of pressure, would you launch your "We stand with the Uighurs" campaign there? Maybe yes, maybe no, but you should consider that carefully. Or maybe you wouldn't want them to gather data on you at all, if you are, say, involved with the Hong Kong resistance or whatever. And maybe, knowing this, you would want to take your data and attention elsewhere just on principle.

Given what we know today, would you trust Facebook to not do any secret shady business with your data? Wouldn't you make that part of a decision where one outcome might give them a lot more data on you?

That's why such info is very much of relevance to customers. That's why they try so hard to control the spin on things like that, because it's harmful if their background gets too much attention.