Is YouTube at fault

I'm seeing a lot of needing to push for stricter gun laws and such as can be expected but I had another thought to the situation of the recent Florida school shooting, the shooter had commented on a YouTube channel he watched saying " I am going to be a professional school shooter" the YouTuber who's channel it was reported it to YouTube as spam and the comment was deleted no authorities had been notified even with the frequency of shooting going on, so here's the question, is YouTube at fault? Now, of course they can't just contact authorities and have all individuals arrested if this happens but the local authorities of the shooter and all neighbors, classmates, and even police suspected him to shoot somewhere up or commit a violent act at some point. And of course, while police just can't arrest someone for being suspicious of the person doing this just off of them trying to hurt neighbors animals and killing squirrels for fun with a pellet gun with the comment on YouTube, if it was brought to their attention would it have made a difference where potentially he couldn't have purchased the gun or might have been charged or on extra close watch especially being his mother died recently and if he ever had a time to go off the deep end it would have been coming.. what do you think, is YouTube at fault for not taking the comment seriously and contacting authorities?

*Just to be clear I am not blaming YouTube or saying I think they are responsible this is just a thought spun off of how everyone says it wouldn't have happened if there were stricter gun laws and if YouTube would have taken more action or the FBI would have would there have potentially been a different outcome.