Anecdotally, I would perceive “Bowing out of this thread” as a more negative response because it encapsulates both topic as well as the quality of my response or behavior of myself. While “not worth getting into” is mostly about the worth of the object level matter.
(Though remarking on behavior of the person you’re arguing with is a reasonable thing to do, I’m not sure that interpretation is what you intend)
Anecdotally, I would perceive “Bowing out of this thread” as a more negative response because it encapsulates both topic as well as the quality of my response or behavior of myself. While “not worth getting into” is mostly about the worth of the object level matter. (Though remarking on behavior of the person you’re arguing with is a reasonable thing to do, I’m not sure that interpretation is what you intend)