I believe there was a time when the auto-generated comment was needed later on, when the question reaches five close votes and the actual redirection takes place. If the comment was removed or changed this could break. Is this still the case?
If not, I could safely change the auto-generated comment and use my longer comment instead. This is not a suggestion to replace the auto-generated comment with a longer text, just an informative question to know whether it is safe to remove or change it.