The issue was a person sold their home subject 2 and the person who bought it stopped paying.

If you made those free they'd be complaining about jobs or supermarket deserts or lack of public transportation or some other issue.

Verify its condition and ensure the seller discloses any known issues.

The issue we are running into is that lenders are not recognizing the excess amount he earns as income, therefore it looks like he will not be able to afford any loans that he would be approved for.

I’m going to disagree with @Chris Seveney and say whether an assignee could force a sale directly would be a state law issue and heavily dependent upon the contract terms. 

Risks include market fluctuations, property damage, tenant issues, and unexpected expenses.

As an investor - if I was putting $125k down I would want title in my name and a clear title policy - so that is where I would have the issue. 

You can sell a property with tenants with no issues the only thing is you wont see as good of a price for the property since it will likely be an investor purchasing it.

I do own two triplexes in Scranton, and I will say the one issue is that you are going to be taking care of the utilities normally if they are not on separate meters, which could take a good amount of money away from your overall cash flow. 

As others have stated this is unrealistic due to arrival time, cost order issues, and volume to make it worth it.