Was Sued by Owner of Company after resigning - Geographer Kaart Employee Review

The day I resigned I was scheduled to travel overseas to do a project the next day. I was scheduled to do 2 days of work in Asia solo. 12 hours before my flight, I received emails saying that my hotel had been cancelled and a new hotel had been booked. A grimy hotel in a shady neighborhood in a country who's language I couldn't speak. My manager's had denied my request to rent a car or even bike and had demanded I walk upwards of 25 miles per day to take pictures of intersections. Under their current pay schedule I would be traveling and working a total of 92 hours at least but could only get paid for 36 hours (no joke). Considering all of this, I decided to resign. About a month later I was served by a Sheriff that my now ex-boss was suing me in small claims court for around $3000 for travel costs, managerial costs associated with my departure, and the cost difference required for a different employee to do the job. You might be thinking... but wait Colorado is an at-will state for employment isn't it? Yes, you're right. There was no legal justification for the lawsuit. I ended up counter suing for a long history of unpaid wages. (upwards of 300 hours). (backstory: We were required to work 12+ hour days but could only log 10 hours. Also we were only paid for a fraction of our travel time.) In the end, I ended up winning monies in mediation. He, losing his preposterous case. Seriously, what kind of company sues their employee's for resigning??