Korzybski wrote, "I accept the absolute individuality of events on the un-speakable objective levels, which necessitates the conclusion that all statements about them are only probable in various degrees, introducing a general principle of uncertainty in all statements." in S&S on page 93.
He means that we cannot know when a statement is "true" in any absolute sense. His claim is that every statement about what is going on is at best only probably in various degrees.
Korzybski's general principle of uncertainty can be paraphrased as a claim that all statements about events in the world we live in are only probable in varying degrees, where the probability of a statement can be thought of as the degree to which the statement approaches "truth".
If you want to suggest that 'subjectivity' is a better term, then I think you are reading more into what Korzybski intended, or you are looking at it from a different perspective.
... we tend to say we can never be objective ... as there is some subjectivity to all reporting given that different nervous systems abstract differently. This is not what Korzybski is saying. Subjectivity, as you are using it here, speaks to "the second umpire" perspective ("I call them the way I see them."), not the degree of truth or falsity on an infinity valued truth scale. "Subjectivity" would call our attention to the likelyhood of competing theories put forth by different individuals. It's a very "political" perspective, as in "Whose point of view can this statement represent, and what are his motives."
How is the actor interpreting the "part" he playing on this stage in this play? Korzybski's general principle of uncertainty has to do with how much fiction or fact the line in the play present to the audience, not how this or that actor interpretes the line.
I'm not sure you meant "precision" in statement. That is something we seem able to achieve. What we cannot achieve is "accuracy" in statement. Precision is getting the same or close to the same answer each time. Accuracy is hitting the target. A statement is accurate if it is "true" or highly probably true, but a statement is a precise description if it is repeatable in the same way.
quote:Accuracy is telling the truth . . . Precision is telling the same story over and over again.
Yiding Wang, yiwang@mtu.edu
Much more succinctly stated than your original formulation. It's amazing how second and third order abstractions can come to the point more precisely. 
(If you didn't get the pun, I'm not going to explain it.)
So, if I understand you correctly, you would like it to be known that "to-me-ness"to Ben formulates as "the general principle of subjectivity", an expression that does not show any (to me) evidence of its formulator. I said it this way, because it seems like an oxymoron to me to formulate "the general principle of subjectivity", when "subjectivity" means something along the lines of relative to different observers - not being able to abstract without the influence of the abstractor - as in my "C" of general semantics - the map reflects the map maker.