After the SL doc, the params allows to pass touches or not, from a child prim to a script in the root prim.
Normally, touches should not pass without llPassTouches( ) set to an appropriate value.
Same goes for the collisionns, which should not pass at all, but they pass... after a 7 minutes delay #157
The choice to pass everything may be intentional, though. But the reason I signal it is that it is related to #157
llPassCollisions shows the same behavior for collisions, even the 7 minutes before actuating.