To publish, maybe. He was at a doctors appointment, got a tip, and passed it to his boss. He didn't write the news alert. If they wanted more context, the other people on the chat should have found some.
That's not how I read the linked story? That particular Slack message happened to coincide with his doctor's appointment, but the article that printed had his byline on it. Surely he wrote it, or at the very least dictated it to an editor who put it in the system. No one publishes stories on the wire based on a two-message slack thread sent from the doctor's office!
Unfortunately, and unless AP releases something further in the way of explaining this, we don’t actually know if that’s what happened.
Their retraction note is very brief, and simply states the information was wrong.
Edit: pasting the entire message
> WARSAW, Poland (AP) — In earlier versions of a story published November 15, 2022, The Associated Press reported erroneously, based on information from a senior American intelligence official who spoke on condition of anonymity, that Russian missiles had crossed into Poland and killed two people. Subsequent reporting showed that the missiles were Russian-made and most likely fired by Ukraine in defense against a Russian attack.
You can see the alert here[0], it does not have any byline. If you view the source of the page it has a "timestamp" like this:
<span class="Timestamp Component-root-0-2-39 Component-timestamp-0-2-38" data-key="timestamp" data-source="2022-11-15T18:41:15Z" title="2022-11-15 18:41:15 - Tue Nov 15 2022 13:41:15 GMT-0500 (Eastern Standard Time)">November 15, 2022</span>
which exactly corresponds to the 1:41pm "alert sent" message in the screenshotted Slack conversation. So they did indeed publish it based on this Slack thread.
To publish, maybe. He was at a doctors appointment, got a tip, and passed it to his boss. He didn't write the news alert. If they wanted more context, the other people on the chat should have found some.