This article seems pointless to me. If Trump was legally obliged to publish his tax return then the Supreme Court could surely order them to be published whether Trump liked it or not. The SC are empowered to set legal precedents (that's why they are called The SUPREME Court,) and so would simply order the tax department to release the information.
If however, presidential candidates are not required to publish tax returns (which they are clearly not given the SC judgement it should not be an issue so why waste energy.
I recall a long (several weeks,) battle I got into on a now defunct site named gather.com a few years ago through trying to explain to a fanatical liberal the difference between tax evasion and tax avoidance. When it was explained that an accountant advised me on arranging finances in perfectly legal to minimise my tax liability, a bunch of liberal zealots (the kind of people who probably didn't earn enough to qualify for income tax,) piled onto the thread, eager to tell me what a vile person I was, how I was guilty of murdering third world babies and how, if I was a decent person I would MAXIMISE my tax liability "to help the poor.
There was no point arguing with these people, they just could not understand the meaning of "I paid what the law requires me to pay," even though it is a very simple concept.
If Trump is cheating the taxman somehow, you can be sure it has not shown up on his tax return.