Why can't I access the profile page of user "?" and block him?

Take a look at this: https://answers.yahoo.com/question/index?qid=20190126041717AAOzso2 Click on the user who goes by the username ? and all you get is a redirect. How do I block this user? This guy keeps posting insults.
Answers

Quetzel

Flag him and add a comment to bring it to the attention of the administrator

Donnie Porko

Because they’re zombie accounts. They got suspended but they can still post hence the zombie name: dead but still alive.

Maelstrom One

This is one of Yahoo! Answers' flaws.