I dunno. You answer the (unasked?) question about a category for William and Mary. And the discussion does show how things evolve in WikiTree. I think Michael might want to still create a _category_ for W&M, and your post is helpful there. Looking at other categories in the Category:Virginia Universities, the category would just be [[Category:College of William and Mary]] (not including city/county or state), as you suggested.
Cheers, Liz