Even though Lu Zhou wasn't familiar with economics, at a place like Princeton, any field of study related to mathematics more or less would be studied by mathematicians.
Especially when it came to economics.
It was very difficult to create novel economics theories using traditional research methods.
Therefore, if one wanted to create outstanding economics research, mathematics was their only way. Even though traditional economists had criticized this approach, it had helped countless students graduate with a degree.
In fact, mathematics was a life-saving tool for any field that required quantitative analysis. It could extract value from seemingly useless data. It all depended on how well one applied mathematical tools to their own area.