It’s something to do with a criminal history or your arrest background. Mesa’s screening process isn’t looking that far into your personal life. All US Part 121 carriers are required to conduct a DOT 10 year work history screening process for your application in addition to other details. All criminal history should be included on your airline apps. If they run the mandatory background on you and find items of significance that you did not disclose like a public intoxication, theft, or DUI...you will likely be disqualified. This background check is to ensure the flying public that the pilots have been screened. Hope this helps.