It's special pleading because the argument itself relies on a rule that applies to everything except the one thing that it is trying to show.
You're proposing a rule that must have an exception in order to show the exception exists. Once you admit an exception to the rule of the ontological argument exists then you suppose the rule to be false and open yourself up to other exceptions to your "rule".
The ontological argument is fallacious because it rests upon a premise that it indeed proves to be a false premise.
The special pleading fallacy.
I'm sorry...
but you demonstrate here (like most atheists I encounter) that you "do not" understand the argument...
Your first sentence "relies on a rule that applies to everything except the one thing that it is trying to show." fully
demonstrates this (that you do not understand the philosophical quirk.. and the logical reason for the philosophical
quirk and how it is justifiable).
I don't personally use the ontological argument...because I believe a case can be made for an equivocation fallacy
..... how the first premise is an issue of concept verses reality. (but I do understand how it only applies to "God." Capital - G).
To falsely accuse the ontological argument of special pleading fully demonstrates that you do not understand
the uniqueness of "special cases." Justifiable special cases are self-evident in reason... unless you have a
bias against such reason (reasoning and logic).
Something is preventing you from seeing the difference in category...which is causing you (and many other
atheists who are allowing their bias to prevent them from seeing such reason) to miss the logic of the special
case.
Justifiable special cases are NOT special pleading fallacies... regardless of the uniqueness of what they
demonstrate philosophically. There is NOTHING else to compare "an infinite being for which nothing
greater can be imagined." It IS clearly a special case... which makes accusations of the special
pleading fallacy easily demonstrated as false accusations IF you understand the argument.
To even compare anything tangible to God clearly demonstrates that the person doesn't understand
the ontological argument. I don't like to use Anselm's argument...or even Kurt Godel's version of it..
but someone is misleading you if they are claiming it is a special pleading fallacy.
False accusations of the special pleading fallacy are so abundant these days it is an evidence that
the philosophical understanding has BECOME sophomoric. In fact, I would be very very very
interested in any publication before 1970 which accused the Ontological Argument of a special
pleading fallacy.