I agree it's very blurred about their usage.
What we do know that is concrete though is that, like you said, they cannon use the name "Marvel"; and they cannot advertise it within 300 miles of Orlando unless it's a national buys - which seems pretty pointless to do something in Florida with those restrictions.
Now this is my interpretation of this part of the contract:
To the extent and in the territories that MCA has exclusive theme park rights, such shall not prohibit (except for the limitations described below) Marvel from itself developing or licensing its planned Retail concept which may include interactive elements as a major or minor element (presently intended to be called “The Marvel Action Universe” and referred to as such herein, but which may also be called “The Marvel Universe” or another name chosen by Marvel).
Since Disney now owns Marvel, this restricts them. "The Marvel Action Universe" was essentially a placeholder name. I know it says Retail concept, but the following paragraph makes clear of one thing:
Mini-theme parks, recreation centers, game centers and the like designated with the Marvel name or the name of any Marvel characters or any major entertainment component of a Marvel Action Universe such as a motion based film ride shall not be within 60 miles of any Universal Theme Park with a THE MARVEL UNIVERSE.
No The Marvel Action Universe shall be in or marketed in conjunction with any themed entertainment areas owned, operated or marketed by Disney, Time-Warner, Six Flags, Sony, Paramount or Busch. As used herein, “theme park” and “themed entertainment areas” shall not include, inter alia, facilities or complexes where at least 70% of the revenues generated on the premises are derived from retail sales or whose primary source of revenue is lodging (which may include food, beverage and gaming revenues).
Basically, Marvel, under the now ownership of Disney, can open a store. Anything else cannot be added. It's not a matter of GotG rights being used, it's a matter of a Marvel property being used so close to IOA. Which is why Guardians usage in WDW has been able to jump thru a bit more loopholes.
Unless an agreement was made, which I have heard has not, Universal can use the above 2 passages and have a legitimate gripe/case.