I don't think that's the case at all. Lots of work was done computerising newsrooms in that period.
True, but as you say the meaning of words shift. It is entirely plausible that they were exposed to the term in its bureaucratic meaning, and continued to it without any connection to actual boilers - the same way we do today.
https://en.wikipedia.org/wiki/SHRDLU https://www.wikiwand.com/en/Etaoin_shrdlu
No one ever called it “boilerplate code” for any reason having to do with boilers or typesetting or water heaters.
It’s a language idiom. It entered common use through reasonably well documented avenues, and that is via typesetting.
We use it because that’s just how language works. All these “it makes more sense to me if it referred to such and such” misunderstand language.