Being opposed to the science of vaccines should tell you he's a guy who won't listen to experts. That's not what we want in a leader, we saw how well that went with Trump.
But even if he was the type to listen to experts, our election process in the US is "first past the post." This makes any third party candidate a spoiler, therefore making it more likely that the candidate opposed to that third party's issues will win.
I hate it, and wish we could do ranked choice or STAR voting to allow viable third party/independent candidates. But we don't. He's a science-denying spoiler and nothing more.