Sorry but, who in politics is not a populist?
However, most people seem to take "populist" to mean "someone who distorts policy questions and advances their own agenda by pandering to people's emotions". I would call such a person a "demagogue" instead.
Your definition is fine but it's the application of the term to specific instances that concerns me. It's mostly used as a surprisingly effective emotive smear rarely accompanied by an argument + specifics that might actually reveal the predilections of those that utter it.