I put it in the "indeterminate" category. If it is Bill Ayers, it's interesting, and it makes if highly unlikely that Barack didn't know who he was in 1983, but the photo is too grainy to give me warm fuzzies about a positive identification. The Frizzy hair and Glasses are the same as in the Known Ayers picture.
I’ve seen versions of this photo that are a little (not a whole lot) clearer, and the clearer the picture is the more he looks like Bill Ayers.
At the time this photo would have been taken - likely Dec 1982/ spring 1983 - Bill Ayers was going to college at Bank Street College (about 2 blocks or .2 mile from Columbia University)
Billy Ayers has never been that heavy in his adult life. Look at the right profile ... now Newman from Seinfeld, well ...