You can tweak saving actions in rules, but I don't see how you could possibly inject rules when first loading SQLTableEditor (unless one went the full "v8 way" with service factories and all that, which is kinda experimental still - and even then I don't know if it'd be possible).
What you might be able to do though, is create a separate External Connection and stuff your encripytion requirements in its connection string - which seems doable with stuff like Always Encrypted (warning: I've not tested it). Even if it's in the same db as the application, the system should just reconnect using the relevant keys and handle everything transparently.
By the way, kudos for trying to do The Right Thing - in 2023 we should be encrypting everything everywhere all the time...
