The NFL did pay that POS, but he began making noise again about discrimination, blacklists, etc., so what is easier - let him have a workout, or fight another lawsuit? Keep in mind that the previous one, Goodell folded right away.
If Goodell & the League are in the clear. If he sues them, then the NFL will claim that he is in breach of their agreement and counter-sue.
Goodell arranged this workout because 2 or 3 owners want cover to work him out without publicly admitting any interest. Goodell is nothing if not a back-scratcher for the owners who sign his monster paychecks.