A semi-auto shotgun would be an option. Less felt recoil and no need to pump the gun. It can be left ready to use.
If weight is a consideration a somewhat lighter gun can be used. You also might consider a lighter gauge than 12.
When you pick a home defense weapon you have to consider the tactics appropriate for that weapon and for the person using that weapon. A shotgun might not be the best choice for room clearing and someone that has problems holding a heavy weapon also might not be able to clear rooms regardless of weapon.
Where a shotgun is superior is in static places, a safe room or some type of bunker situation. That might also be a better tactic for someone that isn't that strong.
So while a weak person might not be able to comfortably tote a heavy shotgun around they could rest the gun on a bed or dresser, keeping an area covered.