These things are all a matter of perspective. For most of the world, Coronavirus is probably the bigger news story. However, for most Americans, Coronavirus is still merely a nuisance.
9/11 Literally shut down the entire nation out of fear and it shut it down very suddenly. I think some people forget that Downtown New York City blew up on live television right before the nation's eyes. Most of the nation watched it happen. It was the first attack on the mainland US since the American Civil War. It was a serious wake-up call to a nation that thought it was invincible. Even if you didn't think the US was invincible, The suddenness and visual impact of 9/11 were very powerful. I remember sitting down at work when it happened and staring at a TV that was in the break room with every employee in the shop. Each employee had stopped working and sat speechless with jaws wide open for quite sometime watching the towers collapse.
While the virus is a serious matter, not once has any news story about it completely stopped me in my tracks - or anyone else I know - the way that 9/11 did. The slow buildup, lack of real shutdowns (outside of sports, travel and leisure activities), and deaths limited to the elderly and those already in poor health really haven't been nearly as big of a shock to most Americans. So, while yes, it would be arrogant to assume that 9/11 affected the rest of the world as much as the USA, from an American perspective - 9/11 is still the bigger news story.
Now, if the US gets put in a China-style full lockdown for a couple of weeks/months or the death count spirals out of control with bodies piled up in the streets, then yes - the coronavirus could become a bigger news story in the US.