What you write doesn't make any sense. You say it's "silly to expect a comment to be neutral" but the comment is "as neutral as possible" and then answer if the commenter was neutral with "yes". Those aren't consistent.

I don't know what definitions of neutral or value judgment you're using, but I hope you can use this as a learning opportunity. The original comment has the obvious implicit judgment that a greater CO2 footprint is a bad thing. This is shared context. It is so obvious it doesn't need to be explicitly stated, any more than "murdering people is bad". The purpose of the comment is clearly to shame the person for having such a high carbon footprint, otherwise there's no purpose in bringing it up. I don't know what your purpose was in trying to deny that. But if you genuinely didn't understand before, I hope now you do, and that this has been helpful in improving your reading comprehension or understanding of shared/implicit context.