That's an improbable excuse, and frankly I thought Thomas would have been more creative...Thomas doesn't have to "understand" the form/s as most people in his position have tax accountants (hell, even I do). Is Thomas suggesting when he reviewed his return/s before signing he never "noticed" his wife's income was not listed so it's not his fault, it's somehow his tax accountant's fault? If he gave his tax acc't the info, it would have been listed!!
If Thomas doesn't review his tax docs before signing, get this guy off the Supreme Court - he probably has a habit of not reviewing critical docs!!