Ah ha! Yes! That's it! Thank you Nikolaos! You laid out the points that connect Seltza's translation with the context.
The Wikipedia article you linked is about Spinoza. Apparently, the last section of his Ethics argues for the notion of amor Dei intellectualis, divine/intellectual love of God.
The other two links you provided quote French author Léon Werth's WWII journal, Déposition.
As it happens, Werth is where I encountered the phrase amor intellectualis necessitatis.
In Werth's roman à clef of WWI, Clavel soldat, a French soldier (Werth himself) at the front is hating the fact that, with death always imminent and civilian ("real") life a world away, no one can get on with living, e.g., do "normal" things. He muses that, for example, he'd like to read Spinoza's Ethics "once and for all," out of "amor intellectualis necessitatis."
It's Werth's play on Spinoza's notion, substituting necessity for God, and highlighting the incongruity of such an abstract desire in so exigent a situation. (Later we discover he in fact has a copy, and finds time to read it.)
Again, thank you much, Seltza and Nikolaos.