While it is correct to use a 404 response code to indicate that something that once existed is no longer found, this may cause some confusion for folks visiting a Self-Evaluation results post in a per-site meta.
From An example Site-Self Evaluation with a broken link in the meta question:
The Site Self-Evaluation review queue is open and populated with 10 questions that were asked and answered in the last quarter. Run a few Google searches to see how easy they are to find and compare the answers we have with the information available on other sites.
At the end of the evaluation, some communities go through the results and fix any problems they see with the posts, based on discussion and feedback. The discussion and feedback oftentimes bumps the self-valuation post to the top of the meta active page. Something feels a little off about leaving broken links in the Site Evaluation Review Queue question, posted by the Community bot.
Thus, here are a few possible solutions to alleviate this potential problem:
The Community bot should edit the question and remove the link to the self-evaluation review queue, once the review period is over.
OR instead, replace the 404 page with something that explains and educates users on the purpose of the self-evaluation. I've seen users go through the review queue like it's a close vote queue or first posts queue instead of taking the time to look at the posts from the perspective of someone coming from Google. Thus, having more persistent information about the purpose of this type of review may help ensure future reviews are treated appropriately. If there is content in the help center about self-evaluations, that would be an appropriate place to link to.
Here is an example of a 404 response to the Self-Evaluation Review Queue: https://freelancing.stackexchange.com/review/site-eval