For a better understanding:
The query member method can accept a Formula object instead of the queryString.
This Formula object can receive a parameter thanks to the querySettings object.
Those parameters must be put in a args object nested in the querySettings object.
The Formula receives this args object as $1.
The Formula must return a boolean result. It iterates on the entities and can use them as This
Your code could be like this one:
// This Formula object receives args as $1
//The query member method can be given a Formula object instead of a queryString
//The querySettings are given ($settings)
$0:= (BB_ISODate(This.Date; This.Time) < $dateTime)