If this happened to a junior, the junior is not morally at fault as much as the adult trainer who likely suggested it. If this is a way to slag the rider rather than the coach, stop this train. It’s the coach who needs to be cited, and (if the story is true) is likely doing this all the time.
A junior rider with a crooked coach tends to have little scope to refuse to cheat. How many of us as adults say OMG I can’t believe what we accepted as normal as kids? Whether that was doped horses in competitive h/j or asshole raw brutality from bad cowboy adults (my world).
I get that you want to gossip about a famous up and coming young rider. But it’s the coach who provided the earbuds that needs sanction.