Curious if they could simply piggyback on the Signal source code. Lots of folks try to reinvent the wheel these days. Just like protocol buffers reinvented ASN.1 + PER and so-forth. Even the crypto folks at protocol labs opted for the former in place of an established standard.
No. I wrote about this a couple of years ago (https://mjg59.dreamwidth.org/62598.html) and the answer is that while Signal solves the cryptography problem, the other hard problem (ie, everything to do with key management) is still up to whatever's on top of the Signal protocol.
