There is no actual contradiction, as these arguments have a crucial flaw that makes them incorrect.

Simply to enter the past is to alter the past, which is a literal and actual contradiction of logic.

This opening section of Q is the origin and precursor of the Valaquenta, as may be seen from the fall of its sentences and from many details of wording; while brief as it is it offers no actual contradictions to the text of the Lost Tales, save in a few details of names.