Yep. I posted this on a different Signal HN submission, but the very next commit on April 22nd, 2020 was when they first began working on the integration.
It could just be an arguably-legitimate desire to keep the hot new feature secret until the big announcement; this particular bit is... sub-optimal... but it doesn't seem like it needs to be nefarious.
This might be a legitimate reason to keep the source code non-public temporarily. However, the communication strategy by Signal about this was horrible (or rather non-existent).
People in the user forum (https://community.signalusers.org/t/where-is-new-signal-serv...) and in other places on the internet were upset for months, because the server wasn't being updated anymore. At the same time, Signal regularly tweetet that "all they do is 100% open source", even at a point in time where no source code was released for almost a year.
Just 2 days ago this was getting picked up by some larger tech news platforms:
It's normal that Signal ignores its users, but apparently they didn't even reply to press inquiries about the source code. All it would have taken is a clear statement like "we're working on a cool new feature and will release the sources once that's ready, please bear with us". Instead, they left people speculating for months.
This communication strategy, combined with the cryptocurrency announcement, may cause serious harm to Signal's reputation.
OTOH, announcing this development semi-privately on GitHub but not to the public at large (including the current MobileCoin owners) could be considered as "insider trading", and it's a criminal offense in US.
