I can confirm that the jerseys definitely do not have to be the same brand. Lots of clubs have athletes with differing personal sponsors, and they find ways to get everyone in nearly identical jerseys. The intent of the rule is that when you look at the athletes, you can tell they are on the same team. Sometimes athletes have additional logos on their jerseys representing personal sponsors and that is not a problem.
The issue from a past year that was mentioned previously in this thread, involved athletes with jerseys that were totally different colors. It was a far more egregious violation of the rule.
This case is borderline, IMO, because Pearson's jersey is only half white on the front, while the rest of the team was mostly white on the front.
It probably would have helped Tinman's case if they had put "Tinman" or something of the sort on all of the jerseys, but the rules do not require that a club name or logo be on the jersey.
It looks like the powers that be judged the jerseys ahead of time and found them to be acceptable. If people don't like how the rule was enforced, complain to the cross country council.
Keep in mind that even if Pearson's uniform was found to not be nearly identical to his teammates, the penalty would simply be that he could not score for his team... and they still win by a landslide. It looks like the rest of the team was matching?
People also made allegations in this thread that not all of the runners actually live in the right association? If you suspect that is the case, please reach out as far ahead of the meet as possible. If someone lies about their address, it won't stand out when addresses are being checked and may get overlooked if no one raises a concern.
And to whoever said the LOC is the one checking on athletes' eligibility, that is not normally the case.