You explained clearly and respectfully with the background info what you need.
They came back with a question. An odd question. I suspect:
* They are not experienced
* They have been “punished” before because someone asked for “X, and common sense implies X,Y” but the requestor wanted “X,Z”. So they ask dumb questions to be sure.
* Not enough coffee, and realtime conversation they didn’t parse what you said properly.
I would take the question with a sense of calm and not worry. It is a good think they are asking questions. Encourage dumb questions. 1% of the time they are smart questions.
As a senior dev it could be your time to shine with some mentoring:
“It would be fantastic to have a stack trace on every log, but I suspect this would cause performance problems and increase our log storage costs. It is sufficient to only have stack traces when an exception occurs”
I guess you said something like this at the time.
By the way stack trace logs where there are no exceptions are something I have done, but not every log.
Aside: A stack trace for every log almost sounds like a cool startup idea or monitoring product differentiator, as long as the UX is good and it doesn’t add noise.