founderBTCout = x BTC + founderBTCin
founderBTCsum = founderBTCout - founderBTCin = (x BTC + founderBTCin) - founderBTCin = x BTC (as xeelee said left pocket - right pocket)
and
foundertokens = founderBTCin * allTokens / (x BTC + founderBTCin)
wich becomes more, if more founderBTCin are spent, what doesn't matter, because they will get it back. So - theoretically - if they borrow and put 1 million BTC there, noone gets a shit any more and after they can give them back without a problem.
Iota, I am not against your purpose, but any argument against this? You have to admit, that this is a valid point of criticism.
You demand trust in this case. We all know that this is not that easy and not the crypto way.