From what my teammate in EV last year tells me, the ES measured the dowel after the first run, declared the violation, and gave them the next few minutes to fix the problem.
It was especially hard for him because they had so much video evidence of the dowel not moving enough to violate the rules in their practice runs, but stuff happened at nationals and they were thrown into a dire and unexpected scenario. The given explanation at the time was not clear to the participants, though it might have been to the super, and the time it consumed hindered their ability to adequately prepare for their second run.
I had thought the violation was due to the dowel being used as a brake when it stopped, but it turns out this was not the case.
My apologies for using the word "disgusting" to describe the ruling, as it appears it was handled fairly and well by the committee (and the event supervisor), and my own team bias should not have been so pervasive when speaking to such an objective matter.