Sorry mate but it's hard to believe!!
Why the D.520 is a tabù when it doesn't fight in BoB and if we take the time from the France invasion we have anyway the M.S.406?
SoW is anyway a new game and I think that can be the opposite and IL2 should make anxious!!
First, my comments about what Team Daidalos or Oleg Maddox might do are speculation on my part. I'd be very happy if I was wrong.
Second, the MS406 got into the game because the Finns used it extensively. It was included as a non-flyable in Forgotten Battles, in 2004, before Oleg even thought of SoW .
If the D.520 saw significant use on the Eastern Front, then I don't think see how Oleg/1C could object to it. Sadly, while the Bulgarians and Romanians ordered some D.520s, reports that they were actually used operationally on the Russian Front are unreliable.
While I agree with you that SoW should have nothing to fear from IL2, Oleg/1C seems to think differently - at least in the past.