Nope, you are right to think that would be the case because you'd think you could just tilt the compass to compensate for the tilt, but the draw-down on the needle due to inclination can be large enough that the needle's pivot point will start to bind up and the needle won't roated freely.

From what I can tell the secret to a global needle is a VERY "tiltable" pivot point that allows you to tilt the compass more than you normally would.

I wish I could find the Silva or Brunton web site where they talked about that.