Dancing on the possible grave of a sick politician doesn't earn his opponent a single vote. The people who are happy about Trump being ill were going to vote for Biden anyway.
However, it does have an effect on the voting patterns of centrists. For example, Fox News' commentator Tammy Bruce was a liberal gay rights activist that had her political views completely upended by the hatred expressed by the left when President Reagan passed away.
So.....best to keep it classy.