Why not? Signal was willing to run all kinds crazy setups to evade foreign laws, like domain fronting.

https://signal.org/blog/doodles-stickers-censorship/

If Signal can do it, then why doesn't Apple make a stand?

If signal doesn’t make a stand, the entire value prop of signal collapses and they cease to be a thing.

For Apple, privacy is one value prop. But seemingly smaller one than the UK market.