HR Help Desk - Can CategoryHierarchy (Category Hierarchical Picker) Be Set as Required in VBS?

We are looking to make our Category selection a requirement for our HR Help Desk Agents, without affecting our Employees (not required for Employees). I was wondering if there is a way to specifically only make the "CategoryHierarchy (Category Hierarchical Picker)" field in Help Desk Requests (Agent View) a required field, when creating and updating requests for Agents:

I understand I could go down to the field-level for Category in Sandbox > Application Composer > Standard Objects > HR Help Desk Request > Fields, and make Category required there, but this also affects the Employee doing it this way, and we don't want to do that: