Liability to new owner of property (mold)

[Konrad R.]

I'm contemplating the purchase of a property. I did a walk through and noticed mold all over the ceiling in the bathroom. The window also had some mold. I'm guessing the mold is from poor ventilation and/or a roof leak over the bathroom. I'm planning on replacing the roof and tearing the bathroom down to the studs. 

The problem is that the tenant does not want to move out. The current owner doesn't seem to care about liability issues. There is also a rotting deck in the backyard that the tenant barricaded off so her kid will not get hurt (I will repair that immediately). 

I tried to add removal of tenants as a contingency, but the landlord for some reason will not budge. I'm planning on trying a cash for keys approach during the inspection period. If that fails, do you think it is too much liability to leave the tenant in place until the lease is up? I don't want to remove the mold while she is living there. I don't want them getting sick during that process. What are your thoughts? I can always back out if the keys for cash does not work.