Do you think if you call their bluff that you will win?

Sounds like a win win for your contractor...

Property is occupied and I spoke with the owner 1 week after winning and told him we want to do a cash for keys, but he was shocked that his house sold and told me that he was still making payments monthly, (I assume now that he was making payments on 200K mrg in 2009.)b.

So the SBA mortgage will be unenforceable against the current owner or the winning bidder at the tax foreclosure sale -unless a payment has been made within the last six years (after 2013).  

You are asking how to win the rat race and win now.

They both have existing mortgages + delinquent taxes - I am wanting to see all options (wholesale, subject to, etc) I can exercise to retrieve the homes and also get more clarity on this question -Why would I purchase their home (after covering the mortgage) + tax liens when I have a possibility to win it at auction for a possible fraction of the price?

definitely on the hunt for some good deals, connections and win win win situations.

If you can get a place that by renting rooms/or Airbnb’s can eliminate your lodging costs in Houston and pay the mortgage I would think that would be a win. 

Promise a WIN & they rush in. 

I recommend you find a realtor who works primarily with investors (buyers do not pay commissions so it will cost you nothing) to come up with a more targeted and winning strategy.