[danielparks]

I’m having a hard time imagining what value putting code names in the crossword would have. Did they suspect the compiler was encoding information in the position of the words or something?

Seems like an unnecessarily hard way to exfiltrate data.

[tempestn]

True, but you can still imagine why they'd be worried to find so many of these related code words regarding the most critical secret operation of the war being published in this cryptic fashion.

[mulmen]

Based on what we knew of enigma and codebreaking at the time knowing frequently-used or high-value words and phrases may have assisted German codebreaking efforts.

Considering the circumstances extreme paranoia seems justified.

[ceejayoz]

If you had limited bandwidth, but knew other agents existed, "have the other guy ask about Operation Overlord" would be a useful message to get out.

[mhh__]

Although one shouldn't assume, the Abwehr was so totally outgunned in WW2 that they did not successfully insert any agents into Britain. All who landed were either converted to double agents (Some just volunteered without being asked) or captured (and presumably some "dealt with")