There is an option to disable appearance camera movement. This stops about 90% of the camera movement - all movement while in appearance mode. It does not stop the camera movement when entering and exiting appearance mode.
I'm not sure it makes sense to stop the movement when entering or exiting the mode.

Many people rely on the fixed pose used in appearance mode, and the camera positioning is a direct tie in to that. It seems reasonable to adjust the camera to match the change in pose.

The entire "Leave My Camera Alone!" thing was created by the original "It makes sense to move" design being considered extremely annoying by some of us. OK, maybe we're just wierd to want to control our own cameras without the system interfering, but still, that was the goal when asking for our cameras to be left alone.

Now that we thankfully have those controls as options, it's annoying that the Appearances one still doesn't prevent movements on entry and exit. Oh, and the movement on exit is HUGE (the one on entry isn't so bad). I think it does a total camera reset.
To evaluate this, try moving the camera around pivotted on some point that isn't the character, and also move it away from the av, and then select Appearances. If you examine various combinations of pivotted camera navigation and avatar movement followed by entering and exitting Appearances, you'll see how daft it actually behaves. Most of the time the avatar is rotated to face some irrelevant direction (always 180 degrees with respect to its original heading, but unrelated to the camera position). And the camera reset on exit is massive and totally bad.
I can summarize this quite simply: the camera and avatar movements assume that you let your camera trail along behind the avatar, so that in Appearances the av is turned around to face you. For anyone else, the av movements are largely unhelpful, and sometimes just funny --- ie. what's the point of having an av that's looking towards the SouthWest switch around to look towards the NorthEast when entering Appearances? None.
The associated camera movements don't have that slight redeeming feature of being funny though, they're merely annoying, at least for those of us who have selected movement OFF and hence want no unsolicited camera movement at all.If you have the 'Automatic Appearance Camera Movement' unchecked then once you are in appearance mode the camera will stay how you position it until you leave appearance mode.
I can't find a way of triggering it reliably yet, but when I find one I'll report it. I think you have some small bugs there.If you disagree please start a thread in the Feature Suggestions forum and I will follow up there.

Here is an additional idea though which may help you resolve the camera movement issue (the av movement is secondary). Why not consider anyone who has unticked both the Edit movement box and the Appearance movement box as being died-in-the-wool and unequivocally opposed to having the system deliver such unsolicited movement, and not do it? That might be a way out, although personally I think that there are only pro-movement and anti-movement camps in the community, without any middle ground. You could of course provide a middle ground undecided tick box.

It is possible to orbit (ctrl-mouse drag) and pan (ctrl-shift mouse drag) while in appearance mode.
To add to the above, when in Appearances mode it is not possible to pivot the camera around any point except the avatar itself. This is probably not an issue for anyone, but exceptions for no good reason at all are not generally helpful.
There's no real reason for changing the way in which the camera operates after you've gone into Appearances mode, it should work as normal. Indeed, Appearances only needs to be a mode in the sense of raising the Appearances window. Even the pose should be optional, because some people want to model changes of clothing from Appearances while adopting their own poses.
As in the case of system-imposed camera and avatar movements, the Appearance pose is a case of the standard functionality doing too much.
No camera movement, no avatar movement, no poses please, unless people specifically select them. Of course, default options that can be unticked (and work!) are always welcome. Maybe some funny person even wants the av to rotate from SE to NW on entry to Appearances, who knows ... make such things as 180-degree rotation selectable options and you have the greatest chance of keeping most people happy. 