(Sheepish chuckle) Well...as Cynthia had established, there were no alternative exits to the main level from the bottom floors. It wouldn't do to have had our heroes trapped down there.
As for an "in-story" explanation...I'd say, because of that, the bad guys needed them on, so they
Glad you liked it, mate!
"The saying implies but does not name the effective agency of its supposed utopia.... 'Needs and abilities' are, of course, subjective. So the operative statement may be reduced to 'the State shall take, the State shall give'."