Basically this is a contradiction:
The popup notice
Please consider adding a comment if you think this post can be improved.
appears after downvoting a locked question
Locked for 24 days. Comments on this question have been disabled, but it is still accepting new answers and other interactions. Learn more.
It was on this question.
I feel this is undesirable behavior, and so I submit this as a bug report. I suggest blocking the comment-suggesting popup in cases when comments are prevented.