You aren't cloning. I don't know where that term came from but it isn't what we do.
What we do is take a cutting and cause it to root. The dna is locked in the cutting. It isn't reassembled from pieces or combined like when mating occurs.
The plant just continues to grow EXACTLY as it was. If a plant can have genetic drift from top to bottom, then maybe he has a point, but it doesn't........