Not everyone believes him. Also not sure he meant for the windows. He could have meant for the doors, or for the sunroof... he may also have meant the very time they put a saber together, back in preproduction, that they used the draft excluders, and then switched to something else before filming, or during filming, or after ANH. It would be beneficial to have access to an actual OT (especially) ANH Hero saber to check what they are made from. Of course, even then, the original parts may have been damaged or lost and then replaced with a later period part.
He may also have been summing things up as much as he could since the Reddit thing and saber video only allow so much time to respond... I doubt he could go into as much detail as he really had for time's sake. Plus he has contradicted himself before, from what I have read.