I am claiming you on the RE side have made the claim a curved horizon can be viewed at all altitudes and are the most biased presenters of a blatant falsehood in the history of humanity.
OK. I don't know what you're talking about.
The claim is that a curved horizon could be observed on Concorde at its cruising altitude.
The RE claim is that this is because of the globe earth and the reason you don't see a curve on a regular airline is they don't fly high enough, Concorde did.
Your position is that the curve observed on Concorde was caused by distortion by the window. Correct?
If that is so then that raises a few questions.
1) Are you claiming that the distortion in Concorde's windows only occurred at cruising altitude? If so then why did no distortion occur when the plane was lower?
2) If the claim is that the distortion did occur at lower altitudes then do you have any evidence for that?
3) What is the difference between the windows on Concorde and other airlines which don't show horizon curvature?
These are not difficult questions.