I think the GM may have been a little confused (or I am) but I do not believe there is a way currently to move a Guild from one realm to another.
Guild transfers do not follow with any character transfers, Guild Lead or otherwise. In fact you could never server transfer with a normal character transfer while being a Guild Lead.
If you want the guild with that name to exist on Dalaran, you’ll need to create a whole new guild on Dalaran.
The Guild Lead and the Guild have to be on the same realm. People now are leaving/creating alts to hold that spot if they are wanting to move their main to a new server and it happened to be the guild lead.