He is attempting to copyright/trademark the lower case "r" as related to his original art.
I'm not too savvy about copyright/trademark law, but there are only 26 letters in the common alphabet. I sure hope that 52 people won't be able to copyright/trademark the upper and lower case letters.
Of course if the letter is a unique artsist created font, perhaps it could be copyrighted, trademarked as an image but once again, it's a very complicated question.