Any way to disable this new smart un-away system?

[Pantz]

Right. Even if it's not the active window. I thought for a moment that I'd solved the problem by alt-tabbing out of the window and then back into the window and AFK status stayed enabled. I then alt-tabbed to the other window again and moved the mouse and the FFXIV window recognised the movement and I was instantly not in AFK mode anymore.

The new auto-afk settings is set that if you enter the auto-afk mode, any action (like moving your mouse) will bring you out of auto-afk instantly. At least that was how I inferred it to be from the patch notes.