It's always satisfying to be certain, but the meaning of words does shift over time, and sometimes words have multiple origins. Assuming that 70s or 80s programmers knew anything about printing presses is tenuous. Given the long assumption that boilerplate refers to plates on equipment and superior fit of "fill in the blank" documents, it seems more likely that this is the intended meaning. Perhaps the term was heard and misunderstood early on? But the proposed origin doesn't align with the community that's using it to refer to source code.
> Assuming that 70s or 80s programmers knew anything about printing presses is tenuous
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 use it without any connection to actual boilers - the same way we do today.
As to 70's and 80's programmers knowing about printing presses I'll point out that a significant early AI program (1968-1970) was named SHRDLU. One familiar with printing history might recognize those letters as part of the second column of moveable type characters on a Linotype machine (and other type-casting machines.) I didn't look up a reference, but I recall that the first row of bins for hand set hot type letters followed the same convention of letter frequency in English text (for english speaking countries that is.)
etaoin shrdlu
That string of characters became more well know due to its appearance in hot type set news papers of the era. The characters sometimes accidentally made it to press rather than being pulled as part of an erroneous line of text.
I remember asking my father in the 1980s what "boilerplate" meant, having encountered the term in a newspaper. He relayed it to me in the legal sense of the preliminary standard matter on a contract. He was a software developer starting in the 1960s so I have absolutely no doubt that the bureacratic usage was well known in those circles.
