I was on-call and a little sleep deprived when this happened, so I'm looking to see if maybe I was overreacting in this situation as I haven't been able to stop thinking about it.

Last weekend my wife (35F) and I (37F) took our daughter (9F) to my in-laws for a sleepover. We pick her up and my FIL (60?M) started ranting about these "hussy" boots my daughter is wearing. I started laughing, thinking he was joking, and he doubled down saying she looks like a hussy and she should t be wearing boots like this at 9. I told him that maybe he should travel out of the suburbs once in a while to see how other people live, as we live out in the country (farmland across from our house) and this is typical apparel and I didn't see any issue. My MIL wasn't home at the time as she was running errands but he assured us she also didn't like them.

Note: These boots don't even belong to my daughter, they're my wife's; my daughter slipped them on as we were leaving as it was muddy.

My two issues-
1. No matter what my daughter is wearing, I feel it's inappropriate to say she looks like a hussy in front of her. At 9 years old, she doesn't purchase her own clothes, so if someone has an issue with her clothing I feel that it should be brought up to us and not discussed with her. Didn't like having my 9 year old ask me what a hussy was.

2. Are these boots inappropriate for a child to wear? Is this the hill I should be dying on?

TLDR: my 9 year old daughter wore these boots and my FIL called her a hussy.

Edit: I wanted to add my FIL is my wife's step father. He and my MIL have been together for 10+ years.