If they make traders post 100% margin on their contracts, a few things will happen:
1) The activity will simply go offshore, to wit: the trading will be done at an exchange in Tehran or Toronto, instead of in the United States where the CTFC can regulate.
2) Many oil projects *rely* upon hedging in order to mitigate the risks of production, and to provide price signals that determine the economics of a project. Without those price signals, those projects simply don't get executed upon, which depresses supply even further, raising prices.
3) Many oil companies would simply go bankrupt as they are short oil right now (products are generally short) and wouldn't have the capital to cough up the margin requirements. This is already happening in the agricultural commodities business.
4) And likewise, users of oil would not have signals on the economics of their projects. Your favourite airline couldn't sell tickets in advance, because they would have no idea whether or not they would be able to fuel up the plane. Or alternatively, they could sell you a ticket in advance, but they'd have to charge you a massive risk premium to account for their own internal costs.
So its outright dangerous to try and regulate commodities speculation, if, indeed, such speculation does exist.