If it's true that it was only for Adderall--and he had a legal prescription for it--I would hope the suspension would be lifted, regardless of what player and/or team it is. Yes, he should have known better and made sure it was OK officially through the League, but an oversight such as that is not worth of a four game suspension, in my opinion. I think , at worst, one game would be sufficient, if anything. A fine would likely be more appropriate. I think Neal has more than learned his lesson by now. If the NFL starts suspending players for 25% of the season for taking medications a licensed physician prescribed for a perceived medical disorder, then they're stepping over the line. Regardless of ones thoughts on the legitimacy of his disorder and the medication itself, the reality is that some people truly do benefit from this medication. It is not the NFL's place to place judgement on the reasoning of Neal taking the medication.
As I said, if Neal's side of the story is true, then I think four games is truly FAR too severe. Fine him heavily or suspend him one game, at most. PFT posted an article about another player that recently had a similar issue and the suspension was lifted upon appeal. Hopefully there's nothing else to the story and the same will happen with Neal. Regardless of whether he'll ever make an impact on this team, he deserves a chance to fight for a roster spot, given his story.