Bullshit. The product was illegal, but the NFL didn't want to commission an expert to contest the vendor's claims because (a) as we know, altering the ball was never that important, and (b) they didn't want to give the company any more free publicity after they had already jumped all over the story. It also could have had a little to do with the company's claims that other NFL teams were using the same tactic. Therefore, the NFL fell back to the non cooperation charge.
From the first (2012) article:
"Now the towel-making company Gorilla Gold has come forward to say the Chargers were using its Gorilla Gold Grip Enhancer towels, which use all-natural resins to improve the grips of athletes in many sports. Gorilla Gold says its products leave no residue on the football and are not against the rules."
Wow! The towels somehow affect the grip of the football without leaving a residue on the ball? That's amazing, especially since they claim the secret is their "all-natural resins". How do these resins remain on the towel and still do their job? I'd assume altering the molecular structure of the pigskin would also be illegal. Maybe it's magic. Yeah, I don't think magic is covered in the rule book. Someone tell Belichick we've found his next loophole! /sarcasm
Following the incident, the NFL explicitly outlawed the product to avoid this nonsensical claim in the future.
As far as using the case as precedent / law of the shop - and that's how this incident came up in the first place - the ruling is what matters, and that ruling implies that no illegal substance was used. However, that ruling is not based in reality.
http://profootballtalk.nbcsports.com/2012/10/23/towel-maker-chargers-were-using-our-product-not-stickum/
http://profootballtalk.nbcsports.com/2015/06/07/2012-chargers-incident-much-different-from-deflategate/