Nobody uses that and I think it was pre-mined. They should have implemented Monero but the UX isn't there. Maybe a Monero light wallet server run by Signal.
They probably avoided Monero to not attract the additional scrutiny. They don't even accept donations in Monero.
They avoid Monero because Signal and the EFF are actually the feds and this is all theater.
I always thought they didn't want monero because they were pushing their own crypto thingy. Which indeed nobody uses.