According to recent reports, Zungu has been released from police custody in the Western Cape although details are sketchy at this stage.
The former Platinum Stars and SuperSport United ball wizard was arrested in connection with a rape case. It is understood the allegations date back to February 2013 when Zongo was on the books of Chippa United.
Johnson says he got on with Zongo when they worked together at Stars despite the player being fired by the club in April 2016 for disciplinary reasons.
The 27-year-old, whose career has been dogged by off-field issues, last turned out for Royal Eagles in the National First Division last year.
"Myself and Zongo enjoyed a good relationship. Under my guidance he played his best football," Johnson tells KickOff.com. "However, he disrespected football. This is something he needs to get right.
"It's only recently that I read that he was in prison and I didn't know anything about that. I hope the prison might have knocked his head a little bit and whoever gives him another opportunity he will grab it with both hands."
The ex-Dikwena boss adds: "There are people that went to prison, they came back and changed their lives. I believe he has opportunities in life, he is young and you cannot take anything away from his talent."