CRLLS
Thinks s/he gets paid by the post
It might also not be good anymore. You could try contacting the mfg, they might be able to tell you if that formula of that age was paintable (or just do it). Formulas for many of these things have changed due to regulations on low volatile compounds.
I had a tube of pure silicone caulk, it wasn't all that old, and it wasn't dried out or thick, so I thought it was OK. But a day later, it hadn't dried at all! Turns out that can happen, the drying compounds off-gas or degrade or something. It was a real mess removing all that gunk. Now, before tackling any big project with silicone caulk, I squeeze some out, and let it dry for 1/2 hour, and it should at least form a good skin by then. If not, toss that tube!
-ERD50
TA, the "water cleanup" statement on the tube would indicate that it is not Silicone. Silicone is not water soluble. It is very likely that it is paintable. Try dabbing a bit of latex paint on a small a small inconspicuous area. If the paint doesn't take, it should be easy to remove.