IRS Pub 519 is a good place to start your education.  However, there is no such thing as a "nonqualified resident alien."  She may very well have become a resident alien when she entered the country -- it depends on all the facts and circumstances.  And if the immigration lawyer is concerned about having a tax return that shows her marital status and income, it's not going to help if they provide one that shows the husband is unmarried.

Head of household. You cannot file as head
of household if you are a nonresident alien at
any time during the tax year. However, if you
are married, your spouse can qualify as a head
of household if:
• Your spouse is a resident alien or U.S. citizen for the entire tax year,
• You do not choose to be treated as a resident alien, and
• Your spouse meets the other requirements for this filing status,

I really don't understand this aversion to filing a paper return when special circumstances exist, like lack of ITIN (and why didn't they think of that 8 months ago?).