On Tue, 2 Nov 2021 at 04:58, Scott D. Randel <amavocet@comcast.net> wrote:

Lately, I have heard people translating {-vaD} as “for the benefit of.” 


Lately? According to the mailing list archives, it's been used since (at least) 1996:
https://www.kli.org/tlhIngan-Hol/1996/May/msg00326.html

I suspect, as others have already noted, that it probably just comes from a rephrasing of the definition in TKD itself.

--
De'vID