Nope american doesnt sponsor clear but with all the free sign ups it is actually slower over at the delta terminal than tsa pre. Lga in and of itself at terminal b sponsors it’s own fast lane as you point out but not sure it is worth the cost. The tsa pre line at Lga terminal b usually moves very fast I don’t think I have ever spent more than five minutes going thru security. The basic problem with the b fast passes is that you have to buy in advance, I think if you could buy them real time when you see a long line they might be more useful but of all the airports I go thru Lga isn’t one where I would really complain about getting thru security