"Because they are possibly wanting to protect their spirituality from those who they view as spiritually weak."
Yet - those same people go out and knock on complete stranger's doors talking to them about [and listening when forced to] their religious viewpoints. Atheists, liars, welfare moms, tax thieves, methodists, muslims. Yet they worry not about 'protecting' themselves from such influences.
I remember that before I 'figured it out', it was always deeply troubling to me when out in service and the elder or elderette in charge that day would refuse to stop and 'encourage' someone who was missing meetings or seemed discouraged. I recall being in that state once, during which time a car group of Jw's stopped to 'work' my street. They filed out and took every house in on my block, leaving the snow on my sidewalk unmarred. The self-righteous asshole elder in charge looked at me looking out the front window of my house, just a few yards away, and never even waved as they got back in the car. I felt the love that day. In retrospect, it was one of those 'key moments' that helped us eventually see through the hate they call love.