No, his logic is sound if you assume the SMW2 title.
It's sort of like the transitive law, in essence. If A=B and B=C then A=C.
Only in this case it's: if A = B and A+1 = C then C = B+1.
Thus if you assume SMW = SMB4 and SMW2 = YI then logically YI = SMB5.
The problem here is that assumption at the start.
Personally, I agree that the Japanese versions of things are generally the closest to the original intent of the creators.
Sometimes, though, the creators are the ones that ask for things to be changed during localization.
However, to the best of my knowledge, I don't think the SMW2 title in the US is a case of the creators asking for something to be changed in localization.
This is really one of those agree to disagree things in the end.
So let's just move along back on topic, no?
Mario's face on the title screen looks a little off, I just noticed.
Looks like his sideburns were shaved off and his eyes look wierd.
Could use a little work.
It's based on All-Stars bonus room graphics?