it’s not like a potential employer is going to check for places you did not disclose you worked at. This was a fast good job, they aren’t going to spend time researching a guy for a minimum wage job. If he lists the job, they can ask him about it and why he left. They can contact the former employer and verify stuff like pay, dates of employment, voluntary or termination, etc. the former employer can legally say whatever they want as long as it’s true, but fear of litigation usually makes companies stick with pay and dates of employment. Even if what they tell the potential employer true, dude could still sue which will cost them money to litigate it, so they just avoid the danger, their goal is to look out for their company, not tank a former employee’s chances at finding work.