Rabbi Yaakov Menken's Torah.org has not intentionally removed Rabbi Slifkin's and Dr. Schroeder's articles from its website.
It appears that the Torah.org search engine does not index features, although it indexes other parts of the site. (Nowhere on Torah.org is this made clear.)
I apologize for any misrepresentation or inconvenience my reporting error may have caused.
Rabbi Menken owns and manages Team Genesis, a webhosting and design firm that does the design and hosting for Torah.org. It should not be difficult for Torah.org to have this apparent technical glitch repaired so its readers can correctly search its site.
Again, I apologize for my mistake.