On his Titter page he says he’s been trying to work things out for some time. Whatever that means.
Most smart people who get substantial income will file both Federal and state returns whether or not they calculate that they owe taxes, in order to trigger the statute of limitations for audits. It sounds odd, still, that the accusation against him is one of not filing, rather than failing to pay taxes due, even though they believe the due amount is several hundred thousand.
I assume that he's been arguing with the state over how to allocate his revenue between different states. That's a common problem in this age of voracious tax appetites and people who work/earn money in different states.
California wants taxes on 100% of his revenue, whether earned in New York or California. New York wants taxes on 100% of his revenue, whether earned in New York or California. I don't know that this is the case, but I would place a wager that it is. As I say, it's not uncommon.
An additional factor that I've run into is incompetence (perhaps, but perhaps malevolence targeted at Obama detractors) on the part of states (Michigan) that sent out notices of non-filing back to 2008. Of course, I had copies of the filings with canceled checks, and of course the state imputed income and tax that I should pay.
It's simply politically motivated harassment, IMO.