To a point.. If the guy get robbed 6 times, is the landlord liable for that?
Apparently, landlords can't be held liable for anything a third party residing outside of the property does on his property. If the robbers are tenants, and the landlord knows who they are, he can evict or have arrested.
Having said that, if there are repeated break-ins, and the landlord fails to replace broken locks or door jambs, the tenant can have that work done and withhold rent to pay for it.
From reading about this case, I read the landlord installed a lock on the window the burglar climbed in, but the tenant didn't have it locked. Was it too warm to have the window closed? I don't know.
As far as moving to a better place, better places don't accept subsidy tenants. If all subsidy-accepting places have a "No Guns" rule, I wounder if that can be associated back to the state or federal government? Since Constitutional Rights are limits placed on government, and the government is limiting his choices of where to live to only gun free zones, are they not unintentionally violating his 2A right?