You can claim "no distortion" as much as you like...
The facts have been, are, and will forevermore be, this:
If you are looking at something with a piece of glass placed in between you and the something being observed your vision is being distorted by the piece of glass.
Plain, pure, and simple.
Drops mic...
End of topic.
That is actually true, BUT you don't see a curved horizon from most commercial planes. You apparently could from Concorde.
The RE explanation for this is that Concorde flew high enough to see a curve, other commercial airlines do not.
Your claim is that Concorde windows had a different kind of distortion which showed a curve in the horizon which other airplanes do not.
So couple of questions about that.
1) Do you have any evidence of that and
2) If that were so then surely the horizon would be curved on Concorde no matter your altitude, do you have any evidence that people saw a curved horizon all the way up, not just at cruising height?