It might be a bit hyperbolic, but the end result is the same. Rather than compromising the integrity of their app, they'd rather no longer offer it to an entire country's market. Whether it is "dumping" the users or "pulling" out of the market, what's the difference? Lavabit shut their entire operation down once they were forced to compromise their system. While Lavabit didn't have much notice, Signal is signaling their intent to their users. If that signals their users to take action by contacting their congress critters to put pressure, then it seems like a good idea.