This means search engines will get the same treatment and not seeing it as a 301 redirect.
NOTE: Their experiment is based on a live page with status code 200 and NOT an inactive page. So if you want to implement this for legacy URLs that are no longer live, you might want to test it out first.
For most of us though, since our site is running on WordPress, we can simply use a plugin such as Redirection to set up a 301 redirect easily.
Few tools to help you generate 301 redirect code