"seller financed" rent-stabilized property

[Pat Bisz]

Queens, NYC. I live in 6-apartment rent stabilized building that the landlord just put on the market. Three apartments are taken-up by my family members, while the other 3 are taken up by other old-timers (grandmas and grandpas). Along with the rest of my family we are thinking of buying the building more because living here for 20 years we call it home rather than because of financial reasons.
I want to propose "seller financed" plan to the landlord but want to know if my assumptions about its benefits to the seller are correct. Namely, by not getting one lump payment for the building, but rather spreading the repayments over a number of years will the seller be protecting himself from being hit on capital gains tax?