If the general-comments module is any indication, then, yes the drop
script should also drop the priviliges. The drop script must undo
all actions in the create scripts.
More in general, AFAIK, the drop script should remove *every* trace
of the module from the database. For example, if your module uses
general-comments you should remove all comments from the db related
to your tables (bad example, maybe, 'on delete cascade' should take
care of that).
