The Help Center says about tag synonyms:
When should I propose a tag synonym?
Whenever you see questions being repeatedly tagged with the wrong or incorrect tag -- or multiple tags that mean the same thing -- it's a good idea to propose a tag synonym.
The tag was only used once, not repeatedly, so I've chosen the more pragmatic way of editing the question where it was used. Pending tag synonyms don't get a lot of attention, because there is no review queue or something for them.