A tenant is harmed and a lawsuit is filed.

Absolutely no harm in letting it play out, especially if you really like the home.

If that seller is harmed in any way (Like their property isn't on the MLS, or if they don't get a market price for the sale of their property, or you get (or your end buyer) the equity from the sale instead of the seller, you could be accused of providing foreclosure consulting services that require a license/registration.

If it does not, it has done no harm.

Negotiated minerals and water rights on the property, removed the single wide on the property, rehab-ed the farm home ($50k), added a stock tank with fish, repaired water well, and changed tax evaluation to 1D1 Wildlife to lower property taxes substantially.

No harm no foul. ;-)

I tell my tenants I can't control what the wildlife do in the great outdoors, after all that is their home.   

When you approach others as the principal buyer, but your profile and discussions on BP and the net reflects otherwise, you are just harming your reputation.

I think that was the only risk I considered and didn't think other harm could come of it. 

If you are dealing directly with the owner, there is no harm in asking, but I imagine most professional landlords are confident in their rental rates.