I could see that if there had been a manhunt for an active shooter and suspect. But in this case the shooter was reported "neutralized".
let me explain my logic.
the shooter was variously reported as down, in custody, dead, and of course you had the early reports of a second shooter (as always).
CNN reported they had a LE source close to the investigation saying that they had found a cell phone which led them to a car, both of these led them to them an ID and they could tie that ID to social media accounts.
then CNN reported, as coming from a LE source close to the investigation, that they believed this man was from the midwest, had traveled to seattle in the past 48 hours possibly to meet someone, and then driven hours south to the shooting site just prior to the shooting, possibly to find a specific target that he had possibly interacted with over the internet.
they then described this man as having been the one that posted his intentions on a website the night before, and linked him as the owner of a youtube account with videos they described in some detail.
so if i was in seattle, and heard that CNN report, i might have gone searching for more information. and what i would have found is many social media sites both naming this man and giving his youtube account link, and other social media account links of his. this is because there were many many people actively "trolling" and putting his name out there as the suspect. as a joke. but this man was actually in seattle at the time, so it all sounded quite possible...
so now if i was in seattle and heard the CNN report, and looked for more information, and then found all that - and then either later saw the man (who has a very very unique look when you see his videos) or i had seen him the night before etc - i might just be the kind of person to confront him, and i might be armed, or i might have 4 friends with me, or any other number of scenarios that would put this man's life in danger.
what are the odds of that happening? i dont know. but i dont think it is a huge stretch to say that CNN's rushed and incorrect reporting could reasonably be said to have put someone in danger.