[kordless]

There is no logical way to verify that all activists (or even a majority of them) use Signal over WhatsApp. The perception that activists use Signal may have been enough to block them, but having a huge backdoor in WhatsApp is reason enough to not take action.

[WillPostForFood]

That's assuming it was a macro decision, and not a micro decision. The govt could have had specific intel on a particular activist, or cell that they knew were using Signal, and shut it down to deal with that situation at that time.

[ycmbntrthrwaway]

Signal actively promotes as activist messenger by using names of revolutionaries and anarchists (Makhno, Proudhon, Masha Kolenkina) all over their website. Just for example: https://whispersystems.org/blog/images/signal-faces.png