Some people did, but not everyone. We get the side from leftists here on Lemmy and other social media platforms that cater to young people on the left, but that's a niche within a niche.

Here are some stats from the Miami herald (media bias says center-left w/ high factual reporting):

In a Center for Strategic Politics poll, 61% of respondents said they have a strong or somewhat negative perception of Mangione, while just 18% said they have a strong or somewhat positive perception.

This was on Dec. 13, just days after the murder.

It certainly sent a message, but that message was different for different audiences.