The plugin works great, as described.
However, here is Google's advice on the subject: https://support.google.com/webmasters/answer/181708
Returning a code other than 404 or 410 for a non-existent page (or redirecting users to another page, such as the homepage, instead of returning a 404) can be problematic. Firstly, it tells search engines that there’s a real page at that URL. As a result, that URL may be crawled and its content indexed. Because of the time Googlebot spends on non-existent pages, your unique URLs may not be discovered as quickly or visited as frequently and your site’s crawl coverage may be impacted (also, you probably don’t want your site to rank well for the search query [File not found]).
We recommend that you always return a 404 (Not found) or a 410 (Gone) response code in response to a request for a non-existing page. You can improve the user experience by configuring your site to display a custom 404 page when returning a 404 response code. For example, you could create a page containing a list of your most popular pages, or a link to your home page, or a feedback link. But it’s important to remember that it’s not enough to just create a page that displays a 404 message.
We ran this plugin for years. Google recently emailed us to complain about too many redirects which is a big problem for mobile users, and when we removed this plugin, we got a second email about all the sudden 404 errors. We checked and many of the links Google was still trying to check on were over 10 years old. Regret using.