Of course it would, you lower the profit margin, the money moves elsewhere, what an idiotic statement to say this would have no effect.
Make the margin requirement on all energy futures to be 75% and raise the capital gain tax rate on this trading as well, and you’ll see the speculative bubble burst quickly.
See #19 for detailed reasons why raising margins won’t have any effect except curtailment of liquidity at NYMEX. No other effect in this world.