Graceful 404s (prevent soft 404s)
Per Google & Guide Addn.
Important:
If Googlebot encounters noindex, it skips rendering and JavaScript execution. Because Googlebot skips your JavaScript in this case, there is no chance to remove the tag from the page. Using JavaScript to change or remove the robots meta tag might not work as expected. Googlebot skips rendering and JavaScript execution if the meta robots tag initially contains noindex. If there is a possibility that you do want the page indexed, don't use a noindex in the original page code.
Redirect to actual 404 page AND/OR robots noindex
Could use pd.DOM.meta('robots','noindex, nofollow');
or similar...
Edited by Lorin Halpert