Changed to "Under Consideration"
Most likely a comment box could only be used at the time of the initial assignment and ONLY within the email notification sent to the official.
It is already possible to add notes to an assignment in the auditing table, although anything entered there does not show up for the official currently.
The assignment form already has a ton of information on it, so we'd have to figure out a way to elegantly add another, potentially large, box on that form which may not be easy to do either. For that reason, it might be something that gets added to the auditing table as a second step - but the drawback there is that the comment wouldn't be included in the email notification.
So - not easy to do but still something we'll consider for the future.