To be honesty, I lack the financial sophistication to appreciate your point about “speculators in aggregate”. Sorry. I’m not that savvy.
Speculators make money when they buy goods at a lower price than they sell them. The act of buying goods pushes up prices, and the act of selling goods pushes down prices. Thus, a speculator who makes money will raise prices when they are low and reduce them when they are high, thus damping price swings.
A speculator who buys high and sells low will raise prices when they are high, and reduce them when they are low. This will amplify such price swings, to the detriment of the market. No law is needed to limit the damage from such speculators, however, beyond requiring them to play with their own money. Speculators who are on the wrong side of the market will increase market swings while they're in, but they'll soon run out of money and thus be forced out.
The only way speculators would be able to, on aggregate, increase market swings would be if those speculators were, on aggregate, losing money. While there may be enough fools dumping money into oil speculation markets to contribute to market swings, any such fools will pay dearly for for their actions.