@Tyler Hodgson it would be a pass for me. Like others have stated when you factor in setting aside money for R&M, CapX, Vacancy, and management (which should be included in the calc even if you self-manage) with both sides rented @ the market rate of $1700 per side per month he's losing money each month. And I don't know that he's really saving that much in rent, if he lives in one side and rents the other out at $1700 and sets aside 30% of that for R&M, CapX, Vacancy, and management each month that means the true amount going toward the mortgage is only $1,190. So he's still responsible for $1730/month himself. Yes, he can get roommates to help mitigate that cost some, but he could also just get an apartment with roommates and not have to worry about tenants, upkeep, etc. (and that's at full market, at $1400/month it's even worse).
Also, don't know this for sure, but I'm betting that the property tax amount you used is the current tax amount. How much is that going to increase in a year or so when they do a new assessment based on the current purchase price. If this was a flip and it had taxes at the old, pre-flip value you can count on a fair increase.
And what if he decides after a year or two or three that he doesn't want to househack anymore or he's tired of roommates or something else changes and he has/chooses to move? He'd start losing money every month. Overall numbers don't lie, this property is too expensive for the current market rent rates.