Is this meant as a back-reference to the things you've already discussed in this thread, or as an intimation of things left unsaid?

The former, but I suppose both apply. Either way I thought enough had been said and wanted to exit the conversation without particularly implying agreement but without making a fuss.either. A simple assertion of position was appropriate. While strictly true saying "further conversation would just involve spinning new ways of framing stuff for the purpose of arguing for a position and generally be boring and uninformative" would represent connotations that I didn't want to convey at the time. The conversation to that point was positive and had merely exhausted the potential. Quit before it is just an argument.

Since you asked.