I had to look at your state, I'm thinking cheerleading might be a bigger sport there.
Our school is nuts -- they made all the girls try out & then everyone made the squad. I was like "WHY did they even bother with try-outs then?" It was a 3 day process and we had to sit there for HOURS waiting for the results -- we were told one time to pick up our kids and then list wasn't posted yet, so had to wait until it was posted which wasn't for at least another hour & DD had told me she was done about an hour before I picked her up.
This was for Middle School cheerleading & Freshman year cheerleading. My DD didn't go out Sophmore year, I've heard that is when cuts are made but who knows. We also have a seperate team for the competitions in HS (there are no competitions in our Middle School -- their season goes from end of October until Christmas break).
Of course, they only had 10 girls try-out in 8th grade. What DD told me was that they took as many girls as they had uniforms for -- in 8th grade, they had extra uniforms.
I also agree, watching it and performing are 2 different things. I guess I would just leave it as without knowing all the details there could be some reason behind it or who knows, the girls could have been staying after for something else and went and watched it? Also, it would depend on how much emphasis is also placed on tumbling which is a seperate try-out (at least it was with DD). In addition, I would wonder how they knew for sure that was the try-out routine and not just a regular cheer that is used regularly.