I don't think Brenok assumed something was not right. He probably wanted the best pilot available and maybe hoped that if this candidate had some stains on his record, Brenok would be able to re-trained Sabal to make him a better officer. But then the gul discovered that Sabal wasn't as bad as his record claimed.
In a Cardassian library
or in a Cardassian gallery
"Reagan, it appears, is really only an ardent unionist if the unions in question are in Poland" - Stephen King, Skeleton Crew