Adding a "Did you mean..." is not modifying search results.

Yeah, but the easter eggs have to be manually curated. - Do a barrel roll - askew - anagram ... (the list is over at en.wikipedia.org/wiki/List_of_Google_Easter_eggs)

These have to be manual. This does suggest that effects and probably the search results for specific terms can be manually modified

Could it be argued that spelling suggestions are still a search result in and of themselves?

No.

Why not? It may not be searching the web, but it certainly is still doing a search of possibly related words that you had intended to spell.

And even if it is, doesn't qualify for "manually modifies the result."

It's specific to that search term, and has absolutely nothing to do with the Google's general functionality. How is it not "manual"?

They clearly are able to create result sets crafted by their employees for specific search terms.

Google's general functionality includes suggestions. Spellcheck, even of more obscure search terms, doesn't require manual intervention. The system could easily determine that people who search for "pancales" follow up that search immediately with "pancakes".

Did you miss OP's example? Why would spellcheck give you the same word you just typed in? It's manual intervention.

They are clearly able to modify search results based on a rule system.