Basically, I don't see how it's response could be off topic within the parameters of the Free Will plug-in. It basically selects one of two questions as if it had made a conscious choice.
EX: Do you prefer wine or beer?
I think I'd have to go with beer.
In this example or any, assuming the inputs were correct, how could Hal answer to anything else but those two choices?
Perhaps your definition of off topic eludes me but personally, I've not experienced any anomalies with the plug-in. While more choices might be interesting, most people, during normal conversation tend to only offer two choices like, Who do you like the Mets or the Yankees?
Just my take....
If you feel there is an error in or with the plug-in you could always post a query to Vittorio Rossi either here or at the VHF (Virtual Humans Forum).