You quoted from his post:
"Publishers then turned around and imposed that agency deal on Amazon, which is the subject of the DOJ investigation. The end result: There really is more competition in the e-book world, but prices are higher than they likely would be if Amazon and others were able to discount as they saw fit."
How can something be anti-competitive if it increased competition? Whether prices went up or down is irrelevant. The whole point of anti-trust law is to make sure that the market has competition. Not to make sure that prices are low.
It seems to me that the real issue is that nobody has figured out the right way to deal with digital goods where supply is effectively unconstrained. We have constructed laws to create artificial scarcity of digital goods. If the government wants to lower the price of digital goods, what they should do is find a way to relax the regulations that artificially constrain the supply.