Last week, four firms owned by blue-blooded merchant bank Robert Fleming were fined pounds 700,000 in one of the stiffest punishments meted out by City regulators over the affair.
The group was also ordered to pay more than pounds 12m compensation to clients after Mr Armstrong was found to have diverted profitable trades to his personal account.
On Thursday, Mr Bateman said he regretted the actions that had led to the disciplinary decision and that he accepted the findings of Imro, the UK fund management watchdog, and its Hong Kong counterpart, the Securities and Futures Commission.
This weekend, however - in remarks that are likely to stir the controversy over whether City professionals should be allowed to deal on their own account at all - he was more understanding of his former star fund manager.
Personal-account trading has also long been accepted practice, although City firms have increasingly banned it because of the conflicts of interest.
Mr Bateman, however, ruled out any further action after Mr Armstrong was also personally ordered to repay $3m (pounds 2m) to clients.
"Some people mourn the passing of a time in the City where strong characters were prepared to take a position [in the markets]," he said, commenting on Mr Armstrong's allegedly maverick character.
"He was obsessive about producing performance for clients ... he was entirely driven by client performance."
He added that reports suggesting that Mr Armstrong was "thinking about his own wealth" were wide of the mark.
Jardine Fleming Pacific Securities Trust, one of the funds managed by Mr Armstrong, was among the top performing Hong Kong funds in 1993 and 1994 - "You don't get that just by good luck," he said.
Mr Armstrong was dismissed in February, after an international investigation showed that, through preferential late allocation of trades, he made substantial profits on his own account, money that should have gone to Jardine Fleming clients.
Fleming also said it had no plans to take a firmer grip on Jardine Fleming's operation in the aftermath of the affair.
When Mr Armstrong dealt in the markets, he did not have any written evidence as to whether he would be trading for a client or himself. After the deal had been struck, however, it emerged that many profitable deals would go to his own account. It left him open to an enormous conflict of interest, leading to the disciplinary action.
But Mr Bateman said that dealing, as Mr Armstrong did, for cash, was completely different from the requirements of dealing for benchmarked equity funds.
While there was "an element of hindsight" in the fund manager's freedom to book deals to different accounts, "he was always chasing after the best investment, and letting the administration catch up."
Even that, Mr Bateman said, was more a reflection of the booming conditions in South- east Asian markets.
He had also agonised over whether he was making the correct decision when he asked Mr Armstrong to leave the company in February - "I spent many sleepless nights over whether I was making the right judgement."
Mr Bateman's overall outlook, however, will come as meat and drink to Jardine Fleming's competitors in Hong Kong, who are eager to capitalise on the firm's woes.Reuse content