Ex-Godolphin head trainer John O'Shea can continue developing his latest venture after successfully arguing he should be fined rather than suspended for his role in his former stable's strangles case.

O'Shea was fined $30,000 by Racing NSW stewards on Tuesday after a penalty hearing in Sydney.

Earlier this month he was found guilty of giving misleading evidence to stewards and being a party to former Godolphin managing director Henry Plumptre breaching the rule for not disclosing Polemic had been diagnosed with strangles.

O'Shea was fined $20,000 on the misleading evidence finding and $10,000 for the non-disclosure of strangles.

In the hearing he said a ban would have a detrimental effect on his new Randwick stable.

"I opened the doors to the next chapter of my training career on August 24," O'Shea said.

"Several staff have relocated to join me. The stable is in its infancy and any period of suspension would be significantly more detrimental than to that of an established institution."

Stewards believed he was aware of Polemic's diagnosis after Godolphin vet Dr Trevor Robson told them he twice informed O'Shea of the diagnosis in August last year.

But O'Shea, who left Godolphin in April, insists he only knew Polemic displayed symptoms of strangles.

Racing NSW chief steward Marc Van Gestel said O'Shea's offending was "moderate" regarding the evidence-related charge and said the $20,000 fine should not be considered a precedent.

A period of disqualification or suspension would be imposed if a breach of the rule "impacted significantly upon the integrity of racing and the ability of stewards to investigate and prosecute breaches."

O'Shea said he was looking forward to returning to training in his own right.

"I'm extremely excited. I'm looking forward to being the sole person who determines my future and no longer being compelled to face the repercussion of decisions made by others," O'Shea said.

He did express regret for his handling of Polemic's illness.

"My inability to take charge of the situation and report the matter to stewards immediately upon suspecting strangles, as I have done so in the past, was a mistake that will reflect poorly on my reputation," he said.

He asked stewards to take into account that Polemic was placed in isolation to minimise the risk to stablemates and the wider racing community.

In their judgment, stewards were satisfied appropriate bio-security measures had been put in place.

O'Shea's counsel Matthew Stirling told stewards the trainer had not compromised the investigation.

"Whether O'Shea knew about the positive swab or not was not going to change the investigation one way or another," Stirling said.

"O'Shea's evidence has not caused the investigation to go off the rails."

Plumptre was fined $15,000 for not contacting stewards when Polemic was diagnosed.

He stood down from his position last month and intends to work as a bloodstock agent.