It could be both.
Allow me to rephrase: He may SEEM heartless, but he's probably on solid legal ground.
How about: He may SEEM heartless, but that's because the complaining would-be renters here aren't seeing the other side. They seem to expect a special entitlement and compassion because of their health problems, but they are unwilling to consider the other guy's situation.
Backing out of a deal and then claiming you are being ripped off is chutzpah. If enough people did this, as I already noted, the guy would be out of business. Or requiring payment in full upfront with no refunds.
SD
On that, my FRiend, we can agree!