Do you have family member tell you what you kid should wear?

My nine year old it staying over night with her aunt and uncle my brother. And she took some toy a pillow and some pjs he just called me and said he better never see her in those pjs again I guess she bent over and you could see her panties. Don't look was my answer and he said well she won't have them when she comes home. If she don't I am going to flip out she loves these pjs. They cam with leg warmer yes I know but its pjs. What would you do I say he over reacted big time.