Taxonomy term (tags) can't be validated

Just a quick note to say that I don't seem to be able to apply validation to taxonomy term tags when more than one term is present in a term reference field used for the token.

With "When the filter value IS available or a default is provided" and "Specify validation criteria" set, I can get validation of the term name to work if only one term is included in the token ("[node:field_tags]"). But if more than one term (tag, in this case) is selected then the validation fails.

The workaround is to simply not apply any validation to the views argument.