[gaius]

Does anyone have any idea what regulations might impinge on Chris's choice of format for sharing his thoughts?

None. People who learnt that their companies are being acquired via public news services are not in possession of any information the SEC would consider "insider".

[saghm]

The author did mention an all-hands with both Red Hat and IBM executives; there's a pretty good chance some "insider" information was shared there

[gaius]

It is very unlikely, because that's just not how this works. Remember all those execs have been in secret talks with each other for months without any employees having a single clue. They aren't going to divulge anything which could threaten the deal, not with billions on the line, not worth the risk that an employee would let something slip or even deliberately leak.

The company would likely be upset if anyone leaked and take disciplinary action, but the regulator isn't concerned with that.