It doesn’t take much for an elderly person in their 80’s to fall over. There are many fall related fatalities or serious injuries that occur at home, before you even consider the contribution downwash can make.
Before leaping to conclusions, this may have been avoidable or it may just be very bad luck.
How many people pay attention to level crossings? I doubt a helipad would be treated with much more attention.
You can’t protect everyone, all the time. Some times people have to take responsibility for themselves.