In my opinion a view controller should only update the model in response to user interaction with the view. If, for example, you have a boolean in the model and the user changes a switch on the view that is tied to this boolean then the view controller can update the model to reflect the user input.
In your example the change to the model is based on "business logic", so the model shouldn't be changed by the view controller. The relationship between propertyA
and boolA
should be managed by the model.