I think the logic goes like this, if the site owner is served a search warrant or subpeona'd for information, they may legally be prevented from "doing something" or taking an action (announcing, discussing, etc) that this has happened while the investigation is ongoing. Not updating the canary is the opposite of "doing something", it requires no action be taken thus the site owner can't get in trouble for it.
As long as the site owner isn't "coerced" into updating the canary . . .
(post is archived)