Found out I was his backup plan

I was chatting with a guy I used to see and we are slowly reconnecting. We’re both allowed to see other people since we’re not exclusive yet. He was on the way to meet a woman for a date and it seemed he was about to get stood up. So, he calls me and asks if I could get ready in 1 hour since his plans with the other woman were falling through. I asked him if I was his backup plan and he said unfortunately yes. I found it to be offensive, not to mention that I was at the gym and wouldn’t have had the time to wrap up and get ready in an hr regardless. I text him after my workout that it was a bit disrespectful to me and my time to try to see me on such short notice as the backup. He said he was trying to salvage his evening and why would I be offended, that he thought I’d be pleased that he was suddenly available. Did I make too big of a deal out of this? Is it not offensive for someone to tell you you’re their backup after their main plan fell through?