Any competent intelligence service can set it up to look like information gleaned from a broken code was found elsewhere, thus denying the tip-off that the code was broken. The Brits did that with the Zimmerman Telegram, for example.
So much for that excuse.
Some secrets you can think you can sometimes risk revealing, and some you can't. Our decryption of the Japanese cyphers was perhaps our most vital secret in the Pacific War. Midway was touch-and-go, and, had the Japanese realized our codebreaking success, we probably would have lost that battle. Midway happened shortly after the relocations.
I take it you would have thought it worth taking the risk of losing the Battle of Midway? Pardon me if I do not agree.