"To enhance the potential punishment from a misdemeanor to a felony, the Government alleged that Auernheimer’s CFAA violation occurred in furtherance of a violation of New Jersey’s computer crime statute, N.J. Stat. Ann. § 2C:20-31(a)"

It's less that US decided to try him in New Jersey, and more that the prosecutors who wanted to try him were in New Jersey. If the US Attorney for the Eastern District of Arkansas had wanted a crack at this case, it would not have ended up in NJ.

[Edit] To be clear, there is nothing unique about the New Jersey statute that was used as a sentencing enhancement. As many states do, Arkansas has a similar statute - A.C.A. § 5-41-104 - so the sentencing enhancement could have been applied with Arkansas as the venue. The E. Arkansas US Attorney's Office exercised prosecutorial discretion by not seeking indictment. The New Jersey USAO decided they wanted to prosecute and thought they could make a colorable claim on the issue of venue.

The prosecution tells us much more about the New Jersey USAO than it does about the overall desire of the US Government to prosecute this particular act.

Makes you wonder if might have a friend at AT&T...

Yes, that seems to be the real reason they picked NJ.

I don't think that can be it. I'm pretty sure they could apply the relevant New Jersey law even if the trial did not physically occur in NJ. For the purposes of that analysis, it would be enough that some "victims" resided in NJ.

The linked-to court judgement says that there are no applicable NJ laws. The relevant laws don't apply, and that it's not enough that some 4% of the numbers were from people in NJ.

I think you (and apparently several other people) have misunderstood my comment: it is clear from the opinion that for 4% of victims to live in New Jersey is not adequate for venue to be proper. The question I was responding to, though, was why the government would want for venue to be proper in New Jersey. It was hypothesized that the government sought to apply some particular New Jersey law. My point was only that, assuming there is some such law (and it appears from the opinion that there is -- though its applicability is questionable), that would not explain why the government sought to have the trial in New Jersey because they could apply the New Jersey law regardless of whether the trial was held in New Jersey.

The more likely explanation, as others have pointed out, is simply that the U.S. Attorney for the District of New Jersey is the one who wanted to bring the case.