FWIW, some additional context. I'm a UK track official (admittedly with the lowest level of qualification) and have worked with several of the officials I saw on the live stream from Watford. I'm also a very poor 800m runner who has 'competed' at Watford Open Meets.
There is no warm up track at Watford and the stadium is on the side of a hill, so you are very limited in where you warm up. Everyone routinely does their strides and drills on the track. There is no pause between races, so there are literally dozens of athletes warming up at the same time as every race. It's never a problem.
Officiating is almost always a miserable experience because a significant minority of the officials are ill-tempered and unfriendly. The way they speak to athletes and the general lack of respect they show - especially to younger athletes - is really depressing. There's no sense that we officials are there to provide a service to the athletes and ensure they have a good competitive experience. For that reason I won't pursue a higher level of qualification and get involved in more meetings than the half a dozen I do each year. The eye witness account suggesting that the official singled out Kyle and placed a hand on him is highly believable and totally in keeping with the sort of attitude and behaviour I've seen frequently. I've heard lots of stories from officials who take particular delight in showing the 'big names' that "the rules still apply to them".