The point is that appealing to social knowledge to resolve ambiguities when it would have been easy enough to speak precisely constitutes sloppiness.

If we're treating "sloppy" as a pejorative, then I don't think this is true as generally as you're stating it. By the same logic, we could say that measuring anything in units smaller than micrometers is "sloppy." Yes, greater precison is always possible, but it's not always necessary. This is actually a clearer way to describe what's going on in the other fork of this thread--we're disagreeing about where the necessary minimum of precision in language is, in that particular case. (At least, that's what I thought we were disagreeing about; if you had a different idea, I suggest we either get on the same page or drop it entirely.)