I agree with this suggestion.
In fact, this suggestion could be expanded on to prevent unnecessary reporting. Some users report other players even when there are no violations. This can actually waste the moderator's time. Also, it's a very important suggestion to include the outcome of a report. For example, if there is a real violation and the report is ignored despite being reviewed, that would be a bad situation. Or, if a report is made unnecessarily, the user could be informed of this.