I think this is correct, but I also think there are two distinct levels to this. Language is inherently relative so when we describe we first must decide whether we have described the scenario correctly. Then we must decide whether our description is appropriate to the world itself. So both atman and pinprick are right, they are just right about different things.

All things knowable (intellectual) are relative.  These things that exist intellectually are constantly changing, exist in time, therefore their relative nature.

I think that's where you lose me a bit because this takes far more rigor to prove than what you have stated. Moreso, I think there are knowable things that are absolute, like math for instance, and since you said all my one example fails your argument.