I read through it, and the only thing I could see regarding the reselling of tickets is at the bottom of page A-2.
(c.) Licensee is acquiring this PSL for Licensee's own use and shall not view to the distribution of this PSL or GIANTS SEASON TICKETS to others, EXCEPT in accordance with applicable Federal and State law;
Well, Stubhub.com is a legal establishment, and is in accordance to "Federal and State laws". So the "thousands of PSL owners" including myself, who sell their unused tickets on Stubhub are "safe" in using Stubhub, in the reselling their Giants season tickets.
No problem, best to base things on facts so we don't have to be hyper-paranoid.