If you look at the SSDI stats: https://www.ssa.gov/oact/STATS/dibStat.html it is interesting to see that when the Financial Crisis happened, the number of applicants jumped drastically; a 34% increase from 2007 to 2009. And as the economy has picked up recently, the number of applications has gone down; a 15% drop from 2010 to 2014.
While I do support the idea of a "safety net", I don't like the idea of people dipping into SSDI when they don't feel like working (or can't get work).
Added later: (1330PST): A lot of people are saying that he could just be having a good day or two. Maybe; but he has enough good days (when I see him), there's no reason that he would not work on his "good days". Secondly: my last conversation with him (3-4 weeks ago) was about how he could go about getting a cash-only gig, and he wanted my opinion (me being a tech guy). I recommended Postmates/TaskRabbit, but he shied away from those, opting for cash gigs from Craigslist. Maybe the 1099 would have ratted him out? I dunno.