He's not officially retired though, NFL.com and various other sites have recently shown videos of him working out and still practicing, he hasn't given up on football yet. So yes, he is still considered a "Free Agent".
I'm not sure what to think of the Moore tweet, or why the college/nfl success even matters, but the fact is, he is only 1 year removed from a team and has one of the largest followings. Just seems weird to not include him in a Free Agent pool with the hundreds of other guys.