do the homeless sleep there to get out of the rain?

Yes they do but they dont bother anyone.

I would assume the homeless sleeps around the Mall during the late evening hours in the doors ways like several other homeless individuals in San Francisco. However, Bart is becoming the most used daytime shelter.

Some homeless people may sit inside to get a break from any unfortunate weather or grab something to eat. Most are friendly people and don't bother anyone :) The ones that do are typically escorted by the mall security, at least from what I've seen.

I imagine they try, but there may be guards to move them onward.