The parent is mistaken. A "false" answer definitely means that no (further) solution exists. You can ask for time or depth limits in practical Prologs, but in basic standard Prolog "false" doesn not mean "could not prove it in time".
Of course some things cannot be disproven, and in those cases (again, if you don't request otherwise) you will get nontermination.
Of course some things cannot be disproven, and in those cases (again, if you don't request otherwise) you will get nontermination.