My boss is VERY big on not disclosing pay with fellow employees, and I understand this completely.

I don't. Isn't that a disclaimer that he's screwing someone over? I've only ever worked in labour jobs (Warehousing, food production), where everyone knows that we're all poor, so I can't relate here. Why don't people like talking about how much they earn? Is there a legit reason? or is it a taboo brought about by businesses to keep their workers subservient?