I think that the basic concept of slightly off-center letters, one element being the wrong size, etc., would be extremely funny if in the context of perfectionism. The Derby opened less than 10 hours ago; I bet that if this entry were withdrawn and reworked to include 13 visual puns (for the letters of perfectionism) the new entry would fog very, very quickly. I would certainly vote for a new "perfectionism" design in the same style, simply to show my support for the artist doing the right thing.
FWIW, my first exposure to Obsessive-Compulsive Disorder was in the latter two books of Orson Scott Card's Ender's Game quartet. For a general audience, it's probably the best representation (that I've read) of the extreme anguish that both precedes and accompanies compulsive behavior - as well as of the anguish of knowing the unwanted, intrusive impulses will reoccur.
The diagnostic criteria for "Compulsions" states (in part) that "the behaviors or mental acts are aimed at preventing or reducing distress or preventing some dreaded event or situation; however, these behaviors or mental acts either are not connected in a realistic way with what they are designed to neutralize or prevent or are clearly excessive" (APA (2000), DSM-IV-TR, 300.3). Are you straightening letters because you're bothered that the letters are crooked? That's not OCD. Are you straightening letters because you believe that your mother might die if any of them are crooked for even a second? That's entering into the realm of OCD.
This is not an area that I know very much about - and obviously there are others in this thread who expert - but after thinking about this for a bit, I agree with those who believe this shirt should be Rejectionator-ed. "OCD" in its non-clinical sense is part of the general lexicon (I wish DSM-V would change the nomenclature), but it's also a severe, disabling disease that can ruin lives and marriages, result in the loss of jobs and educational opportunities, and can be excruciating. Treatment for OCD has improved greatly and many individuals with OCD can live productive and enjoyable lives, but that doesn't diminish the severity of the disease or increase the appropriateness of this print - especially in this Derby. (And if you want to be technical, OCD is a disease and not a "personality deficit.")