I believe in the past there were a least two other members of this forum that were at clubs with rules around low level optional gymnasts going to regionals.
In one case the gym wouldn't take the athletes unless they had scored a 36, the idea being that if the gymnast was unlikely to be competitive they were better off switching back to skill development and preparation for the next level instead of what is essentially another meet at a time that is not convenient for the gym's long term athlete plan.
In the other case - they would only take the athlete if they made the all-star team for what I believe are similar reasons.
It is possible it is also partially logistics - taking the coach/es away while the upper optional are preparing for their championship season can be very disruptive.
Sometimes it is more an elite mindset, gymnasts need to earn that opportunity/reward by getting to the higher levels of the sport.
Airborne is from all appearances a very strong gym with a history of strong upper level/elite athletes. It looks like a few of last years level sixes skipped ahead to level eight - so if that is the plan, a few extra weeks on working routines that are already of excellent quality is cutting into the time the gym would rather spend on developing future level 10/elite gymnastics - There seems to be a bigger picture/goal and that is level 10/elite and I am sure the families are well aware of the gyms goals.