That's great, for you. The suit isn't alleging that raising the price to pay for free shipping is illegal. The suit is about controlling the market and hiking up the price to pay for your free shipping across the market.
Ie, it's fine that a retailer charges $15 + free shipping, instead of $10 + $5 shipping. It's not fine to them force the price on all other retailers to sell at a minimum of $15. Especially not since they probably have to charge shipping.
The argument that this violates anti trust is because it raises the prices for everyone, not just the people who are fine with hasslefree free shipping