You mentioned a loophole, not a deal. Which is it?
The contract spells it out. Its characters in use in IoA and members of those characters families. So because Hulk (and others obviously) is an Avenger, any Avenger is off limits for Disney to use. Same as Disney can't use Venom because he's a Spider-man character.
Guardians of the Galaxy were not a member of any related property until after the deal was made, because the Guardians team that most people know of (the MCU version) is not the old Guardians team.
The contract spells out the US 'east of the Mississippi' as the location for the contract to be valid, which is why DLR is a totally different animal.
This is the actual contract:
https://www.sec.gov/Archives/edgar/data/1262449/000119312510008732/dex1057.htm