The state of Massachusetts has a commission against discrimination.
http://www.mass.gov/mcad/regs804cmr0200.html
“Applicable Law. The Massachusetts Fair Housing statute, as contained in M.G.L. c. 151B, s. 4 prohibits discrimination because of race, color, religious creed, national origin, sex, age, ancestry, veteran status, sexual orientation, marital status, children, handicap, and receipt of public assistance or housing subsidy in the selling, renting or leasing of housing accommodations, commercial space, or land intended for use as such.”
Sounds like this landlord has just opened the door to a major can of whoop-ass.
If anybody opens a betting window on whether the commission will even lift a finger to assist the prospective renter, I'll put my money on the "NO" side. I could be wrong, just a feeling.