I'm not certain that these are "Varsity" Xs. Those are more block-like and are not solid Xs like this guy had.
I think he was found wearing socks but no shoes. Correct me if I'm wrong. Another thing that strikes me as interesting is his lack of shoes. Someone that is THAT tall would wear a very large sized shoe, at least I believe that he would. Shoes like that tend to have to be special ordered. So, is it possible that he was homeless and none of the shelters had shoes that fit him? Just trying to think of all possible angles.
I believe he deliberately ditched his footwear because that would make his identity easily traceable due to length and width of the shoe. It fits with his act being well-planned. Lack of shoes, penned message/toe tag on foot protected by socks, possibly the name of a tenant (given to the doorman) and knowledge of an empty apartment in the selected building all point to advance planning. Also, he was determined to get into that elevator quickly and was on the ground within minutes.
Personally, I do not believe he was homeless nor had he used the city shelters.