So let's reason from first principals:
1) We want btsx to be valuable.
2) We want bitUSD to be worth $1.
Given these two desires, we need to create self reinforcing incentives that drive people towards both of those goals. If a minority of actors defect from those goals, they should be "punished" by losing value, whether they are holding bitAssets or btsx.
Some other truths:
1) the value of btsx relative to actual $ has been volatile
2) the value of bitUSD relative to actual $ has been volatile
3) bitUSD is (obviously) only priced in btsx.
4) we need shorts and longs in equal supply, because only when someone goes short can someone else go long and create bitUSD.
5) paying longs to hold bitUSD with transaction fees is good for them, and creates incentives for them to hold it.
6) forcing shorts to put up collateral btsx is good for them collectively, because it sequesters btsx and drives up the value of btsx. This enables shorts to make money.
6a) forcing shorts to put up collateral btsx is bad for them individually, because buying btsx is hard and a short doesn't have an infinite supply of btsx.
6b) Therefore, we have what in economics is called a collective action problem. The more shorts that short and the more collateral they put up, the better it is for them as a group, but each short wants to defect and let the OTHER shorts put up the collateral. Of course, since we demand a fix amount of collateral now by protocol, they can't defect. They can just choose to sit out.
7) If the peg isn't holding, it is because the short demand and the long demand are imbalanced. Therefore, we want to add longs when there are lots of shorts, and add shorts when there are lots of longs.
The obvious solution to pay the group that is insufficiently supplied. Any other solution will simply cause the smaller group to sit out. Since we are already tapping transaction fees to pay longs already, and they still seem to be in insufficient supply, where can we get more cash? They answer is from the group that is in larger supply. Just add a fee paid from shorts to longs (or longs to shorts, depending on the market). The fee should be something that is part of their bid.
Let the market decide the fees, and the peg will hold. No feed from delegates required.