Yes, at the 3 minute mark..... You are suppose to be there a half hour early, (in the building). That being said, sometimes things are unavoidable, car actually broke down, or big accident that holds everyone up,,,, but just being lazy is a scratch.
I wouldn't scratch them unless this was a repeated issue the parent was warned about, or they missed the entire warmup such that it would be a safety issue to have them compete the first event. I've never had that happen, but if it did I assume they could warm up in time for the next event. In my state we've even had children be allowed to compete that last event at the end of the meet if they need to qualify to states or something, the head judge and meet director will make it happen.
It just so happens that this situation involves my daughter and another team mate. I was running late from job 1 and had my dd ride with someone. Parent was not given a warning and this isn't a recurring issue. Unfortunately I wasn't working the meet with this coach or I would of given him a piece of my mind before the comp started. When my daughter was crying after her comp when she told me what was said....that coach got an ear full!