From a reader:

Jonah,
I think you must have misread that piece. The essence of insider
trading law is “abstain or disclose.” That is, the holder of material
nonpublic information must either not trade on it or disclose it to
the market and then trade on it. (that’s a gross oversimplification,
of course).
The piece might have been talking about other parts of the securities
laws that require issuers and related entities (and dealers &
underwriters) from saying certain things during the time surrounding a
registration statement, but I think it’s poor analysis to say that it
prevents people from releasing factual information.
But I know you don’t want to have that argument. Still, it’s a gross
misrepresentation to argue that insider trading laws as such violate
the first amendment at all, given that the purpose is to encourage the
release of material information.

Me: This reader may be entirely right about all points. I may be misrembering the piece — it was at least a decade ago. But I think folks get my general point, and I won’t be debating the niceties of securities regulation when I don’t know very much about the subject and I have to get back to work.