I assume it's temporary, with the introduction of a new tech it takes time to set regulations and norms for it. That said, I disagree with this stance if it's permanent, but I'm not nearly as cynical about this as most of this chat section.
The X-Games is a sporting event where folks risk their lives for our amusement. So giving competitors a few years to learn if a new technology, a technology with different centers of gravity and moments of inertia, can behave in a predictable manner while performing aerial stunts is a reasonable stance from my perspective.
Otherwise people may rapidly adopt the new tech in competition which could result in bodily harm, battery breaches etc. After all, we aren't talking about just riding the bikes, but hurling them through the air and slamming them onto the ground. I see a real possibility of a breached battery (an extremely high energy bomb with fast and slow release potential) and an unconscious rider creating real harm.
I'm curious of others' views on this take.