Should I report this behavior to my principal?

So a student in my class decided to refuse to go to STEAM class while every other student left. I wasn’t going to force him to go to the class and if gets a zero he just gets a zero. So he just stayed in my classroom while I continued with my planning period.

The student was bored because all he had to do was sit down and stare at the walls. He approached me with a smile on his face and touched my chest. I quickly took his hands off me. He then proceed to say “take off your bra now!”

I I know he is only 9 and I’m an adult but is that sexual assault?

Edit: I will definitely report the students behavior. However what do I do if a kid refuses to leave the classroom? I don’t want him to be physically moved by adults to the office for refusal to go to class.