According to the philosopher William L. Rowe,
"agnosticism is the view that human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist"
The word "rational" is entirely subjective. It means to do something for a "good reason", but "good" depends on ones ethical assumptions, and thus, it is subjective. The rationality of a utilitarianist will be different from somebody who ascribes to Kantian ethics, and so on. Therefore, in conclusion, is agnosticism a subjective position?
For example, take agnosticism with respect to a benevolent human-like God and agnosticism with respect to the spaghetti monster.
If one is agnostic with respect to the Christian God, one may be so because one finds it rational that such a God could exist or at the very least that one does not see any rational reason for why such a god doesn't exist, where one has used some subjective measure of rationality. But that does not imply that one is also agnostic with respect to the spaghetti monster, since one may equally say that it is rational to believe that such a being doesn't exist.
Therefore, since the decision to be agnostic with respect to some belief is entirely subjective, does this mean that the typical atheist argument of "oh so you are an agnostic? Then you must be open to the existence of the Spaghetti Monster as well, you fool!" falls apart, since it ignores this subjectivity?