This is an interception scenario, no?
If issued intentionally, traffic will pass through hardware in… unfriendly territory.
> First, BGP generally prefers the shortest path and yours is going to be a little long, so unless the best original path is very long you need on some transit provider to use policy-based routing and trust you as transit.
the article states:
> The leaked route is likely preferable because of a localpref setting which would prefer sending traffic for free through a peer regardless of the AS path length, over paying to send traffic through a transit provider.
This happens legitimately, e.g. when an end-user becomes multihomed or starts using anycast, so the trusting peer can't necessarily discover this algorithmically. Route signing helps.