Blind people navigate the world by counting steps between landmarks in their world. Ray Charles (though he could probably afford nice hotels) always stayed at Holiday Inns - because the layout of the rooms (at least in that era) was the same, no matter where you went. There was an old joke about how Helen Keller's parents used to punish her - moving the furniture. As insensitive as that joke might be, it's true - if you're used to doing something without looking, re-arranging things makes it a lot harder. I play without looking at the fretboard much (again, LOTS of practice so I don't need to look to see where my fingers are) - I know where I'm going, I use my eyes to gather cues from other musicians, from the audience, etc. Move where the notes are on my fretboard, it's like re-arranging the furniture to a blind person.
Perfect pitch is relative pitch taken to the extreme. Relative pitch means you can figure out from where you are, how to get to the right note - you have some memory of where the right note, is, but it doesn't persist - you can adapt, because your memory is flexible. Perfect pitch means your memory is NOT flexible - it's not about where the note was a few seconds ago, it's always in the same place; you can't move it in your mind - it's THERE. If you played a virtual reality game, where things in the virtual world (what you're seeing) were exactly the same things as in the real world, but every thing was 10 feet North of where you saw it, you'd be bumping into things, and falling off ledges all the time. Pretty much the same thing in this case - I have a mental picture of where to go that doesn't change; by re-tuning the bass, someone has moved the real world on me.