There is no guideline.
"Do not use this tag" is something the community made up to deal with tags that should not be used, but cannot be fully removed for some reason. It doesn't really work, for the most part; people use the tag anyway, despite the warning.
Tag problems are caused by people who don't understand how tags work. It's not completely their fault; tag norms are very site-specific. I frequently find myself wondering how to tag things properly every time I encounter a new SE site.
Editor's note: Some sites, such as Super User, have formalized tag cleanup processes, e.g. by adding status-planned to tag burninate requests. In such cases, it may be considered OK by the community to add that to the tag. However, not all sites support this. Check with the local community before doing so.