Well, he did diagnose the situation correctly. He couldn't comprehend the confusion of ideas that provoked the question.
I'm also not entirely sure it's an odd question to ask. To this day, users are surprised when their software produces garbage output instead of failing. Perhaps the members of parliament were expecting some form of input validation or sanity checking out output.
Would have also been a fair point if Babbage had channeled his inner techbro and insisted it would directly replace human calculators; simple machines like Babbage's will chug along blindly on obviously erroneous data, but humans for all their sloppiness can often backtrack on errors.
I suspect their sarcasm might have escaped Babbage who seems to have been on what we now call "the spectrum."
Isn’t there a saying about there being no stupid questions, only stupid answers or something?