Creators Syndicate interview questions

Editing test, Phone call with Jack Newcombe, then on-site interview with three rounds. Final round with Jack and his father. Received offer and Jack asked when I'd like to start. I proposed a date and he asked if I thought I'd be ready to work. Gave me time to consider when I'd like to start because he wanted me to be rested and prepared. I emailed him a proposed start date within the time frame he allowed. I also asked whether wage was negotiable. I didn't receive a response for a few days. When I reached out to follow-up, Jack notified me that this wasn't going to work out because he had a "bad feeling" when I didn't immediately accept, asked for a later start date, and asked whether wage was negotiable. Despite attempting to clarify the situation that I only asked for a later start date because he seemed to encourage me to and was merely asking if wage was negotiable, he revoked the offer without allowing for a phone call between us. In short, I feel giving me an offer then rescinding it because I wasn't eager to accept without considering the terms was extremely unprofessional. Thought the process and employees I interacted with via interview were extremely kind so I was caught off-guard by the complete 180. Glad I didn't end up working for someone who expected immediate compliance without question.