I'm not sure I'd even call "local debt" technical debt in ordinary circumstances - realistically there's always going to be mess somewhere, and encapsulating it away where it can't hurt anyone is normal. If it probably never needs to change unless requirements change (in which case any other implementation would also need to) it's fine.

Perhaps if 24 minion instances constitute an actual problem (rather than just inelegance) their example for it is actually foundational debt related having a "minion" being the simplest primitive that would do the job when maybe something lighter could have existed.