TNT would have been cool
Turner broadcasting might tried to sue for tiefin the name.
Its is not a brand name, its simply an abbreviation so no one with sense was going to sue for anything.
TTO is perfect for us and is already being used as we could clearly see at the recently concluded World Relays.
They did not go with T&T or TNT because the IAAF never use any of the letters from the word "and" or the symbol "&" in their three letter abbreviations for countries.