Have you been to America? Plenty of leftists around the country fly American flags.
You can use Signal with a different client. Signal being operated within the US has no effect. As of now the jurisdictions that I know of to be worried about are:
Sweden, where a law is proposed to add an encryption backdoor
The EU, where leadership is pushing for an encryption backdoor
France arrested the founder of Telegram for using end to end encryption in Telegram
Australia in 2018 passed a law that enabled the government to require communications platforms add a backdoor for government decryption. The Director of the Australian Security Intelligence Organisation (ASIO) said that “privacy is important but not absolute”. Which has the same vibes as "this is not about human rights, this is about human life."
WhatsApp was previously suspended in Brazil for refusing to hand over decrypted messages.
China and Russia are very obvious problems. Here's an easy one of many examples
The White House both in Trump's first term and in Biden's presidency were pro-encryption. Signal and Tor were US government funded projects. That's not to say the US is great on encryption, and there have been laws in the past that did/were proposed to limit it. But, as of now, it seems that the US is (edit: one of) the most hospitable jurisdictions for encrypted messaging non-profits.
BTW, I'm not saying using Tox is bad, or that Signal is good, I'm just talking about the US jurisdiction part.
This is a really bad argument that people use. Plenty good causes have lost.
The issue with the Confederacy is that it was a really bad cause, fighting for the enslavement of millions for generations.