What about the third possibility of neither being selected? Boolean can be True, False, or Null. I remember back in my training they recommend setting a default value for boolean values to True or false so that null is never an option.
All of my filters are fairly static, their not based on a value so I have no experience with what you see. I know that calculation happen after read or before save so I suspect that same will happen with filters, they calculate after reading the data so that any changes won't change the list of data you see. I bet someone else will be able to confirm one way or the other.