Cecil Moore wrote:

To the best of my knowledge, the only argument we have left
is whether there is enough time for wave cancellation to
actually take place.

You mean that bit about how you think the waves first move in the
reflected direction a little tiny bit and THEN cancel? Yes, you do need
to rethink that. If they're equal in amplitude and opposite in phase,
there's cancellation - at any value of t. In other words, the waves are
prevented from reflecting. They don't reflect first, then disappear.

73, AC6XG