so if a character is immune to mind effects, for any of a million reasons, and it pics up an intelligent item are they immune to the ego will save?
You mean Immunity to all mind-affecting effects (charms, compulsions, morale effects, patterns, and phantasms)?
Since the Will Save to resist is never stated to be a [mind-affecting] effect nor a charm, compulsion, morale, pattern or phantasm then I would not say immunity to it applies. Immunity to [mind-affecting] is not immunity to will saves just because most will saves are linked to [mind-affecting] spells.
Just my two cents.
From a game-balance perspective: if the 1st level spell "Protection from Evil" could hedge out the influence of end-of-game items (the sort with Ego scores high enough to challenge the PCs), then that just wouldn't make sense.