All that needed to be maintained was that the Klingons we see Kirk face in TOS were all afflicted by the virus - while it’s still reasonable to assume that, the presence of these hitherto unseen 3rd variant of Klingon complicates instead of simplifies, which is what ENT’s arc did. Now what, it’s ANOTHER coincidence that THESE klingons are even ridgier than we’ve seen before, but the other ones are still out there? To borrow your parlance, the Discovery redesign was intended to overwrite and replace what came before, because apparently Star Trek, unlike every other fantasy and science fiction thing I like, is Forbidden from being treated like a secondary world that should have its own internal consistency.
I was completely content to accept it was a coincidence that Kirk only saw augment virus-impacted Klingons in TOS, just like how ST Picard ended up establishing for Romulans (northern vs southern to explain the v shape bone ridge they had through TNG-ENT).