Those "off beat" non topical responses are called
by Hal when Hal really has no suitable topical reply.
Instead of a blank or an I don't know reply, Hal will
simply choose one of the non sequitar responses.
Simply pose another question / statement and Hal should
respond more "in beat" IF Hal can find a topical reply.
It might seem to be a round about way but it does help
keep things flowing.