Is my MIL a “Karen” for not allowing my kids to explore the house?

I have two kids, 7M/5F. My MIL treats my son like a small adult, but my daughter like a baby, even though I say she needs to be treated like an adult. I know she wasn’t raised like this, but I always give my kids the ability to explore new places like someone’s house. I don’t just drop them off anywhere for obvious reasons. Recently at my MIL’s house, I asked her to show her the rooms of the house so she will know her way around. MIL said “What? No! I don’t want anything touching anything! She’s a child and will break something.” I told her that if that’s the case, my kids won’t come over anymore because my daughter isn’t a wild child or a jerk. Now MIL is mad at me for saying that and my husband is starting to get mad at me also, but I feel like my daughter needs to be able to learn to explore like my son. I don’t want her to be treated like a baby forever.