"One tiny company" is Nubank, with a $70B market cap: https://finance.yahoo.com/quote/NU/
_A few employees_ they acquihired support Datomic.
If those few employees quit, get fired, get transferred to some other project, etc., then no more Datomic support.
It’s perfectly reasonable to not want to use a DB that isn’t open source but Datomic isn’t a side project that’s on the edge of not existing.