John Mackey is blogging again.

After the Whole Foods CEO was outed as “rahodeb” – the anonymous poster on Yahoo Finance’s stock message boards who invariably defended the company and argued with detractors – he stopped blogging on the Whole Foods Web site. Company lawyers advised him to stop all Internet activity while the Securities and Exchange Commission investigated whether he had done anything illegal.

The SEC has decided not to pursue any action, so Mackey’s back. While he will likely be more careful about his online activities, he doesn’t seem to have learned much from the experience.

In his first new post, on May 21, Mackey wrote:

My mistake here was one of judgment — not ethics. I didn’t realize posting under a screen name in an online community such as Yahoo! would be so controversial and would cause so many people to be upset.

He argues at length that posting anonymously is “a great ‘equalizer’ between people” in that it gives the arguments themselves more importance than the people making them. “The true identity in the outside world is irrelevant for purposes of participation in these communities,” he wrote.

This is disingenuous at best and delusional at worst. If all posters on a stock message board are just other investors debating the worthiness of a stock, then sure, it doesn’t really matter what their real names are. But if one of them is the CEO of the company under discussion or a competitor — but is essentially pretending to be just another shareholder — then a deception has taken place.

And judging by what was posted on the Yahoo message boards after Mackey was outed, a lot of the participants surely felt as if they had been deceived.

Mackey doesn’t elaborate on how his deception was ethical, or on how it is a simple matter of “bad judgment.” He just says it is.

The government was particularly interested in Mackey’s posts about Wild Oats Market, a competitor that Whole Foods eventually acquired. The SEC wanted to know whether he was trying to manipulate Wild Oats’ stock before the acquisition.

He noted that he didn’t really say all that much about Wild Oats, and that in the period before the acquisition, he didn’t post anything about that company at all.

On the latter point he is right. But there’s just something unseemly about a CEO disparaging a competitor anonymously in an online message board. Mackey, a libertarian, actually evokes the First Amendment in his apologia, and of course he has the constitutional right to say anything he wants. But we’re talking about actions here, not words. And even though he has been legally exonerated, what he did was deeply wrong.

And then there is the most puzzling question of all: Why was Mackey doing this in the first place? He said he took to the message boards because he loves a good debate. OK, so couldn’t he have stuck to discussions about gun control or school prayer? As a commenter on Mackey’s blog wrote: “You should stick to other things, like running a grocery store chain.”

That’s true now more than ever, as a look at Whole Foods’ recent results will tell you.

A CEO blog can either be a repository for banal PR messages, or a real attempt at transparency and dialogue with customers. Mackey’s blog was always pretty good before this mess. Now that he (it must be hoped) will not be spending his online time anonymously playing around on message boards, maybe the blog will be even better than before.