MySQL: Reference aggregate function in conditional select
Cleaver.  But no go.

To achieve what you ask for would take two passes over the data.  Things don't work that way.

The first pass is to find the max for each group; the second pass is to check all the value against the maxes.

You can do it with a subquery, an @variable or several other ways.  Follow the tag to see ways to do "groupwise max".