What people have been saying, is that if most CEOs do insider trading, and only a few have charges brought against them, then that might indicate an abuse of power.

Since the other CEOs (those whose companies wilfully broke the law), weren't investigated, it's a little difficult to be sure so long after the facts. As far as I know, none of them have been indited for helping the US government break the law - arguably a more serious crime than insider trading.

The argument is that it's an instance of: "You bring me the man, I'll find you the crime."[1]

Now, it could be that in the telecom industry at the time, in the US, there was little or no corruption and insider trading, and Nacchio was an exception. I certainly don't think he was framed. But there are at least some indications that it could have been a "tit for tat" that landed him in prison.

[1] (reportedly stated by Stalin's chief of secret police, Lavrentiy Beria -- but I've been able to find a source).