Essentially the Mastermind would always get -1 Attack as long as it wasn't in the City due to whatever reason and had Villains next to it.
I had always assumed these cards referenced Villains in the Bridge as being adjacent to the Mastermind as well. But I guess, in theory, you could really just place the Mastermind wherever. Like if you had Ascending Masterminds, would they be adjacent to the Bridge? There's only one Mastermind slot right there, so if you put them on say your table, what are they adjacent to?
I think it's just coincidence (and good design sense) that the Mastermind slot is near the Bridge.
Somebody pointed this out to me after I interpreted "The Captain and the Devil's" "Dino-Roar of Triumph" wrong.
Burn the Fearful (5 copies)
Choose a Villain or Mastermind. If there are no other Villains adjacent to it, it gets -1 Attack this turn.