They couldn't make Deathknights since they wouldn't have a character of level 55+ on that server.

Level 1 and go, go, go!

That's what I was going to say ... Once blizz fix the DK creation on other realms bug, you'd have to level to 55 before having a DK.

The other bad part, is that they will allow you to create a DK on one server (one with your lv55+ char), then transfer that DK onto another server ..

.. However, you cannot create any more DKs on that account. Not until "open DK creation" is available ..

You can make a DK on any realm as long as you have a level 55, regardless of where it is, even if it is on a different realm.

You cannot do this right now. That was the plan all along, but it was recently changed - right now, DK creation, according to numerous threads here and on the official forums, is limited to the server on which your 55 or higher currently resides. They plan to open up DK creation to all the realms soon, but it is not available right now - unless something has changed in the last few hours.