I think the "why" of that question is important; Why have they refused available shelter.

If it's a legitimate safety issue that isn't addressed, then a homeless individual may have a legitimate case for sleeping on public property. Statistics ay show that, overall, shelter and housing is generally safer than sleeping rough, but statistics look at groups, not individuals, and individuals get singled out. Putting them in shelter or housing (collecting all the eggs in one basket, soto speak) can make them as an individual an easier target. If they are able to find a secluded public place, away from a known area of target, they could potentially be safer. Statistics are good for overall bottom lines, not an individual's personal safety.