I'd need to read more about it, but I don't think that's right.
The "do" character that means "shrine" or "sanctuary" is a different kanji than the one used in "Nintendo."
The reason for this is kind of complicated, but basically the character for "temple” in Japanese is 寺, usually pronounced "tera" which literally means "temple" which basically means "demarcated space" (like a sanctuary) but also implicitly refers to a Buddhist demarcated space. Shrines also use the demarcated space character (寺) in their names, but to implicitly refer to a Shinto demarcated space the character takes on the "do" sound (actually making it more similar to the "to" in "Shinto"). Of course, these sounds are interchangeable and don't always distinguish between Shinto and Buddhist, but that's where things get really complicated.
So although the "do" character in "Nintendo" has the same sound as the "do" used in the names of Shinto Shrines, it is a different kanji. The "ten" 天 character is where "heaven" comes from, and the "Nin" I'll have to take their word on what that means.
The article also references "Tengu," which are mythologically very complicated. For example, if you've watched the movie Spirited Away, Yubaba is a "Tengu."
The author may be right, but I think it's a huge stretch. Pretty cool though, if you like etymology, which I absolutely do!
