If the allegation that there are no comps is true, go get a commercial loan.

If this is as serious as they allege, they need to GO, move, give them their deposit upon moving. 

What’s their alleged justification for fighting this fact?

This:"BUYER UNDERSTANDS AND ACKNOWLEDGES THAT THE PROPERTY MAY BE ENCUMBERED BY MECHANIC’S OR MATERIALMEN’S LIENS OR OTHER LIENS, JUDGMENTS OR ORDERS RESULTING FROM ALLEGED VIOLATIONS OF LOCAL ORDINANCES AND BUYER IS TAKING SUCH PROPERTY SUBJECT TO THOSE LIENS, WHICH MAY OR MAY NOT IMPACT BUYER’S ABILITY TO OCCUPY OR TRANSFER THE PROPERTY IN THE FUTURE."

But this property was going to take more work now, and absolutely more work in the future, than I am willing to put into it. 2 units vacant for over a year (out of state owner, hasn't tried renting them out, allegedly). 1 unit in the middle of an eviction. 2 units filled on MTM leases.

When you don't pay them rent it can be physically dangerous (allegedly).

How do you quiet title against a co-owner, what do you allege as to why you have better title to 100% of the property than the other guy? 

I can be blatant about describing this because I've never been a builder's in-house pocket lender, so no one can point at a past transaction of mine and allege funny business.

Allegedly they saw violence next door and also had a gun pointed at them.  

The fact that there are even posts on here alleging "BS" shows the stereotypical response from countless people who draw conclusions before getting all the facts.