Just guessing but:
- He's gay and that might turn off some swing voters especially people who are already hesitant about having a black woman at the top of the ticket
- He's never won any election beyond a municipal one, so he may be seen as electorally untested.
- His resume is a bit thin with just his time as a mayor of a small town and time as the transportation secretary.
Yeah, the title could have easily just been: "Supreme Court upholds ban on emergency abortions in Texas" and it would be way clearer