If "undervoting" is a valid method of (not) voting for the position of mayor then it is also just as valid for governor or president.  If one doesn't like "any of the above", surely one doesn't what their vote counted as support for a candidate "just because" and possibly be included in a mandate?

As David points out:  "Undervotes are not just casual omissions; they are an intentional and revealing calculation. When considered in the context of total votes cast, undervotes are an indication of how much support a candidate actually has, or doesn’t have, regardless of 'winning.'"