Shiels took over as Morton manager last month but has so far chosen not to speak to the press after games, citing a medical condition that leaves him "emotionally imbalanced" and feeling "an urge to tell the truth".
Shiels was disciplined regularly by the Scottish Football Association for his outspoken comments during his time as Kilmarnock manager and has now decided it is better to remain silent rather than risk further sanctions for speaking candidly.
David Hopkin, his assistant, will now handle all matchday media requirements, although Shiels, a regular pundit on radio, will still deal with journalists on other occasions.
"I have spoken with the doctor and you get emotionally imbalanced," said the Northern Irishman. "It's important I don't compromise my position as manager of Morton Football Club. There's a name for it - you can't help it. If someone asks you a question, you're emotionally imbalanced at that time and you feel an urge to tell the truth.
"And, if you feel hard done by, you want to tell the truth about something that happened in the game and you become a victim of that. There are people out there waiting for you to drop your guard.
"It's my nature, that's the biggest problem and Neil Lennon has that problem too at Celtic. He will tell you he is the same - when you are passionate about something and you put all your energies into it.
"I am probably not intelligent enough to deal with that because journalists can catch me. I don't think it's fair to condemn Scottish football. It's not their fault, it's my fault.
"Journalism in promoting the game is so important and the Scottish journalists are brilliant at it. Every decision I make must be in the best interests of Morton and I'm very susceptible to being controversialised and it's happened to me in the past. I'm not going to go down that road anymore.
"Therefore, in the best interests of the club, I think it's better that David Hopkins does that on matchdays. David is very articulate and can put our point after the game."