There is nothing wrong with paying as little tax as you can if you follow the rules and have the correct documenation. Tax avoidance(otherwise known as planning) is fine. Tax evasion is not.
Idk what trumps taxes show, but as you and i eluded to, he could be racking up losses. Then when he sells the property, he has a massive gain and pays a bunch of taxes on that (the basis would be minimal, especially if held long ago and heavily depreciated).
Not willing to judge until i see them. It is interesting that he doesnt want to. Personally, i would want to wait until.an irs audit was over too though. If they adjust a bunch, id want to wait until after adjustments were made. Its still kind of a cop out though. He could release past returns that arent currently under audit.