I believe he is trying to say that 1) drawing conclusions from the one-time observations of a single individual is unlikely to be accurately representative of the actual situation, and is at great risk of all sorts of selection, recall, and confirmation biases. 2) in that context, ignoring all the other managerial responsibilities of a mayoral position so you can engage in a relatively non-scientific attempt at information gathering when you have people you can consult who are experts on the topic and have spent years studying and collecting data, is quite rightly a poor use of time.

I think you two might be talking past each other here. There's nothing wrong with a politician (i.e. an elected leader) getting first hand experience with an issue. Many leaders do this all the time and get depressingly little press for it--and others do it purely for a PR win unmindful of the cynicism they're generating. I think this mayor was sincere in his intent, and also I think it's a good habit to assume positive intent (to be super corporate about it).

What I think people are taking issue with is the Mayor's seeming dismissal of some homeless as irredeemable, and his failure to acknowledge that homelessness is more than an issue of mental illness, substance abuse, and personal responsibility. That plays into the common stereotype of unhomed people, and as many pointed out, that makes the problem worse because it justifies doing little to solve the problem.

So while I believe the Mayor's intent was good, I also think he was misguided and a little arrogant. I'd be pretty peeved if my non-technical boss did a coding boot camp and came back all "huh I did that camp and I was right, your job isn't hard at all!"

It's also worth saying you don't need to go urban camping for a week to figure out how to solve homelessness. It's probably more effective to just go to endhomelessness.org.