He also states they don't have enough for the down payment (which he says he needs $230k for the downpayment).

@Alex ValenzuelaFocus on loan term if they don’t negotiateAmortize it over 30 years and your payment will be peanuts.

Would I assume liability for non payment?

Your local PHA may also have resources to help match landlords with eligible tenants.The PHA must approve the lease agreement, ensuring it complies with Section 8 rules and rent limits.Pros:Guaranteed Rent Payments (sometimes even 100% based on certain tenant criteria)High demand for Section 8 rentals, which can reduce vacancy periods.Many Section 8 tenants prefer to stay long-term, reducing turnover rates.Cons:Properties must meet and maintain HUD's health and safety standards, which can involve additional maintenance and inspection requirements.The PHA limits how much rent you can charge, which may be lower than the market rate in some areas.Tenants must qualify for Section 8 based on income level and other factors, which may limit the pool of potential renters.Dealing with government agencies can sometimes be time-consuming and bureaucratic.In summary, converting your home into a Section 8 rental can be a good strategy for attracting and maintaining long-term tenants due to the stability and reliability of government-backed rent payments.

IM USING HARD MONEY SO THOSE MONTHLY INTREST ONLY PAYMENTS ARE KILLING ME ASWELL 

Citi Bank just came out with a low down payment, no PMI option for certain neighborhoods.

Should I at least offer to pay the down payment?

The best solution in your situation would be to get a non-owner occupied loan with no pre-payment penalties to buy the building then cashout refi in September when you move. 

The most important thing to consider would be that if you're using your HELOC for down payment / renovation costs and holding costs, then the refinance MUST get you all of your cash back to pay the HELOC back to 0.

I wanted to get into a quadplex but came to a realization that it was too far fetch for me when my lender ask I need to have 70K total (down payment/closing & 6 months reserve) for a 535k quad.