Perhaps an important note is from a Vice article that I found: “..encrypted messaging programs which route messages through the firm's own servers”. If the messages are encrypted on the device then why would you need to send them via the firm’s servers? Maybe it prevents traffic monitoring or something? Sounds more like copy and decrypt.
Also a phone which is obviously only for criminal use does not seem smart - for the same price one could buy a new phone, sim, and popular encryption apps every month. Although a “care-free” solution for criminals is probably appealing.