That does not make sense to me. Since both have Nazis, then that allows the usage of tags to say it involved in Wolfenstein? Also, I can get Discord is wildly used in pc gaming, but it is not used exclusively for that.
I just assumed it was tagged under that because it was the closest thing they could get to 'relevant tag'.
(speaking as someone who once published articles on sites before myself)
Unless you listened to specifically "Oldies" radio stations you would never have heard the song. It's older than what is generally considered "Classic Rock".
This isn't some obscure indie guy though. It's an old hippie from a whole other era - huge in the US prior to The Beatles / British invasion. He's old enough to have grown up during what the franchise used as the idyllic base for their "Pre-War" fiction. Any expectation that this really old guy would somehow be on top of a single franchise in this generation's pop culture is kind of ridiculous.
If anything I'd say the fault is with Universal where they're the ones who apparently have control on the use of the song they should also be responsible for ensuring the artist's approval upon application but prior to actual marketing usage. Then again Universal is probably loving the free press for a legacy artist that most people had probably forgotten was still alive (he's 77).