My understanding is he isn't wanting to sue to get the day trade margin applied to lower equity accounts. He wants the PDT 3 day trade in 5 days restriction removed. I agree with that stance. It is anti-capitalist to tell someone when and how often they can deploy his or her capital in the capital markets.
There was a book?! It was surreal how bad it was save for Bettany's acting. Dude was the movie. They didn't even mention the copula or how it became this lightbulb moment. Just poorly, poorly written (albeit PB's dialogue was good). Nobody can run VaR or vol-shift on a portfolio. Hmm, sure, ok.
I am hardly an expert on stock trading, far from it. I get both sides of the argument. FINRA, NASD, and NYSE are SRO’s and they can set their own equity and risk rules. And for that matter Brokers can set more conservative margin and capital requirements. My sense is that if the PDT rule was somehow overbearing that with all of the political clout the trading exchanges and Wall Street possessed that it wouldn’t be a big ask to change the rule.
I think the exchanges want the rule in place to cut down on administrative costs. They don't want to have to clean up after a bunch of 10 lot day traders each day.
I should really lay off the social media while trading. I didn't read this very carefully. The Big Short is a great book though. I didn't really enjoy the movie.