Presumably in his application cover letter, he explained how his skills from one job pertained to the other. Via Philly.com:
About four months after being defrocked by the Diocese of Camden in 2002, Thomas Harkins had a new job as a security officer, including patting down passengers, with the Transportation Security Administration at Philadelphia International Airport.
The TSA hired the former priest before completing a background check, the agency recently confirmed. According to a church document, the diocese revealed to the TSA in 2003 as part of the background check that Harkins had been removed from ministry because of allegations he had molested two grade-school girls. Harkins was never criminally prosecuted, but the diocese settled civil lawsuits for $195,000.
The TSA took no action as a result of the disclosure. “An allegation alone does not warrant dismissal or automatically disqualify applicants from employment with the TSA,” spokeswoman Ann Davis said.