He's obviously an entitled prick with a bad attitude. It's your business, so you pick and choose your hours, including hours you'll answer answer enquiries.
A lot of men forget, they may be able to pay our rate but that doesn't mean we'll accept them as clients.
I bet they wouldn't be happy answering the phone and dealing with work questions when they go home on an evening or on their days off.
Clients that don't respect you have a life outside of your job or not clients you want to see anyway x