If you’re calling the InternalSession.SESSION threadlocal directly, then you don’t need to go through the rest of the Perspective context - you can directly call whatever you want to - ie,
InternalSession.SESSION.get().getEventBus().post();
Also, a healthy disclaimer that while it’s unlikely we’ll change things, the InternalSession threadlocal is not considered part of our API surface, so it could break in some future version without notice.