I figure it will entail: 1) jackhammering, 2) removal of rubble and dirt, 3) pouring a new concrete floor.

If he coulda done it himself with the home depot 100 dollar tub, and knew how to do it, and we were certain the drain alighned in the concrete foundation, I would have recommended it in a second, and really I tried to hint it so I didnt have to do it.

Basement slab pour and finish with polished concrete was done at a total cost of 16 $ per ft.

The seller is not interested in participating in any owner-carry scenarios but I can ask again if I had a more concrete proposal.Is there a origination scenario that would meet most of my goals? 

In this case, I would do absolutely everything you can to reconnect in 1 day.We just had a leak way behind a bathroom vanity and had to rip out all vanity, sink, cabinets, drywall and concrete block etc.

She's an older Polish woman who just wants take care of her grandson all day.Now getting to the question - I'll probably be paying for the maintenance and other expenses related to this house myself, especially if I'm the one receiving the rent checks.  

The association is saying this because the association owns the walls and the concrete slab.  

Ever see concrete in a toilet?

It depends on what is directly underneath the laminate floor, is it pores material that will absorb it such as wood or is it a vinyl or concrete underpayment.

I would keep marketing, maybe try a new channel or two with a different demographic, keep polishing the place up, and accepting applications until you get someone who meets your criteria.