In a standard situation, a transit network would announce your own routes as well as your customer routes, to your peers, transit or other customers. Peer to Transit, Transit to Transit or Peer to Peer should never be done.
It's meant as no criticism but "should" always worries me in contexts like this. I find that often the reason it's "should" as opposed to "will" is because there's potentially dangerous human input somewhere in the process - as appears to be the case here.
It's hard to be comfortable when this is true of systems as important as those which route the internet or PKI, for example, because it's impossible to know what might happen next. Perhaps it's erroneous to take the "structure" in "infrastructure" literally but in the context of the internet that word is becoming increasingly misnomered in my mind.
