i wonder if some of the "runners" have done a meet. common courtesy if you aren't actually running or throwing is scratch, ideally while the heat sheets can be adjusted. failing that, your coach at the scratch meeting or you before it starts, tell the official, scratch me. that way they don't have to spend time awaiting your turn over and over, they skip to someone else.
now, to be fair, sometimes folks make nominal symbolic attempts. you make the olympics but pull a hammy. you go to tokyo, get in the blocks, stand up. or sometimes folks have a bad day and either make crap performances, foul them all, or even scratch themselves it's so bad.
it is so NOT normal to walk in the ring, healthy, put shot to chin, then walk back out. i ran most of a decade and never once scratched or nominally performed. the kids did not step through and foul, or drop a short measurable toss. they in fact intended to convey their readiness to compete, "except...."
NCAA has a rule where this wouldn't fly, but this is kids, and even at college level i don't know if i care one way or the other on that unless you actually disrupt others. states might have some rules but that's not the issue here. this is a coach's decision. i think it's contrary to the spirit of taking kids to a meet, contrary to the basic courtesies meets get smoothed by. i think in terms of the sport it's an indulgent act, but not a red card, so to speak. but there are many things which while not red cards from the authorities, might get you benched by your coach.