Not sure I'm an expert, but I did get an "A" in contract law, so let me take a stab at lawyer-splaining ...
The "Marvel Action Universe" is a very specific thing--a Planet Hollywood/Dave & Busters rip-off themed to Marvel characters (mostly the ones in IoA, who were the ONLY characters all but the geekiest of fans would have recognized in 1989). Planet Hollywood and Hard Rock were all the rage at this time, everybody was trying to cash in--for example, the WWE restaurant/"experience" in Times Square. Or a little experiment TWDC was working on called DisneyQuest.
MAU is by definition not a "theme park." A "theme park," given the explicit definition in the contract, would be Magic Kingdom, or Sea World, or an as-yet-unbuilt but still easy-to-imagine-in-1989 Six Flags Orlando or Tampa park. Most of the contract is devoted to making sure no other theme park gets to use the IoA characters (again, the only ones with pop cultural relevance at the time). It is very much directed at making sure no other theme park builds rides, shops, restaurants, etc. with Spidey or Hulk. Especially a Six Flags park if the Marvel characters ended up in WB hands, a distinct possibility given Marvel was teetering on the edge of bankruptcy. I seriously doubt anyone who drafted this contract thought WDW would ever want the characters but a new Six Flags or a Six Flags rebrand of one of the AB properties was certainly within the realm of possibility.
Universal didn't want a MAU opening up on I-Drive (Pointe Orlando would've been an obvious target, with FAO Schwartz and Pac Man Cafe) or that rumored new Disney Springs development. That would dilute the market, so close to home. But it wasn't such a huge deal that they felt the need to block them all over the country. A Marvel restaurant/gift shop with a couple traveling mall show level simulators in NYC or Chicago wasn't going to hurt IoA anymore than DQ Chicago hurt MK--if anything, it promotes the IP and lets Marvel make a little extra cash to stay in business publishing comics (again, a real concern back then). So the rules regarding MAU are far more lenient, but in theory still could be enforced if, say, Disney moved to open a Marvel restaurant in Disney Springs. However, those clauses will never have any effect on anything done in DHS, EPCOT, MK or DAK, because those are theme parks, not MAUs or a concept evolved from MAU.