Just leave. If your coworkers and bosses want to text you, they'll do it via Signal.
Umm, no. I use both WhatsApp and Signal (way before this hysteria began) but the "just leave" mentality isn't realistic. Most people don't care about this stuff enough to install a new app and start using it. Even for people who will join it, it takes time. The network effect is still there.
Being on HN too much and/or having social circles full of people who think like you misleads people.
Oh, but it is. You just need to accept a drop in your social circle.
Saying "i'm on signal" could be totally considered normal in just a few weeks from now.
"It's not how the world works". Of course it is. Most people downloaded WhatsApp because someone told them to so they could message each other.
You essentially have a personal disagreement with the practices of a specific company and want to inconvenience others who might not think the same way. It's arguably a selfish perspective, family members may be willing to bend to those demands for an individual. But to expect businesses to indulge every single individual preferences for how they wish to be contacted is impractical.