I do not have permission quite yet but am already in a discussion with Gallahead about this but I am looking to continue ThinkTankUI as an ElvUI extension/edit. Here is a link to the album that I sent him and I am looking for feedback/future testers to give it a go to see if it runs smooth for them. Check it out and let me know your thoughts. (This is not a published UI and will only be published with permission of Gallahead, which seems quite likely, so just sit back and enjoy for now)
You mention that you don't have permission, but I'm genuinely curious... What about that UI makes it unique and requires permission to distribute? To me, it just looks like a normal UI with standard elements (created by any add-on already available today) and typical placement of said elements.
Unitframes in the middle of the screen? Check.
Action Bars somewhere below unitframes? Check.
Minimap in one of the four corners? Check.
Player/Target/Party Buff/Debuffs available? Check.
Tooltip re-skinned? Check.
Nameplates re-skinned? Check.
Chat add-on? Check.
SCT somewhere on the screen? Check.
DBM or other raid add-on? Check.
Several non-standard fonts used throughout UI? Check.
What I'm getting at, and I'm not trying to be a jerk, is that there doesn't seem to be anything custom or unique about the UI which makes it stand out or looks as if it requires any permission to re-create and distribute (e.g. LUI / RealUI). So, is there custom Lua or art or something else which can't be seen in your screenshots that makes it special?