[nikcub]

There's a cost/benefit tradeoff to blocking each service and different governments have different thresholds.

It is more likely that the cost of blocking Signal was negligible in contrast to the benefit, while blocking WhatsApp would likely have huge cost - especially in a country that has only recently experienced a number of citizen-driven coupés.

It is also possible that they're specifically targeting a group (Muslim Brotherhood, or Jund al Islam and other Sinai insurgency groups) that utilize Signal.

[niksakl]

this https://news.ycombinator.com/item?id=13390564