While the in-game shop is available in the WoW Classic client, Blizzard does not have the ability to disable it for specific servers (such as SoD realms).
SOD transfers are not available and I already recommended they put a warning inside the game about that. It’s on the site or BNET shop though that you can’t transfer.
If you’ve recently bought the transfer token you can request a refund.
Even in regular WoW you cannot use paid transfers to bypass realm locks anyway.