How I imagine what’s going on:
Blizz-1: Now how can we spoil the fun for players moving from SoM …
Blizz-2: No idea, we promised free transfer.
Blizz-1: I got it. Listen: We offer free transfer to ONE PvP and ONE PvE realm in each Classic Era and Wrath Classic.
Blizz-2: But what about PvPers having both Ally and Horde players in SoM.
Blizz-1: That’s the beauty of it, just listen to this:
… Additionally, we’ll soon be removing the restriction from Classic Era realms that prevents players from having both Horde and Alliance characters on the same PvP realm. This should make it easier to consolidate your characters in the same place on Classic Era, should you choose to move your SoM characters there. We know many Classic Era players have gathered on realms such as … Firemaw and Pyrewood Village in EU, and due to that consolidation, this change seems appropriate.
We blame it all on the players as usual, and t the same time we get yet another Retail feature in through the backdoor. Soon people will be complaining about lack of character slots, Then we - reluctantly - give in and give 20 per realm.
Blizz-2: But what about the RPers, and the non-English speakers
Blizz-1: Just forget them, they make some noise and stay anyway.