Whats the problem with him doing it ?
The problem is that it seems he's already "succeeded". He made the original layout in an image and effectively said "see, it's possible! Now you have no excuse not to do it" to which ED replied "it looks good on paper but actually doing it physically doesn't work".
So they arranged for him to actually get the parts to try, and now that he's hacked it together and given it a play he's back to "see, it's possible!"
Except it doesn't matter if it is possible or not: the majority want a 4 button layout, it has to be possible to fit AND not interfere with the 4 button layout.
The negativity he's getting now is prelude to the inevitable "I proved it could work, why did you still go with the inferior 4 button layout?" posts he'll make when he ultimately fails to convince ED his solution is viable. Every post he makes about how to get the 6 buttons on without addressing what the majority (and especially EvilDragon!) want just digs that hole deeper.
Don't get me wrong, I want him to get there: it would be great if everyone can win, getting the perfect four button layout and two extra buttons that also work great for arcade style games. But if he's only focused on physically getting the six buttons on there without even thinking about how a 4 button user will use it then he's not going to succeed, he's only going to hurt himself.