It is true that Singapore inherited the defamation laws from the UK. However the UK has taken large legal strides in recent times to update and develop the law as the world of communication changes.
Singapore however has failed to even address the 400 year old law and the government still chooses this means as a way for them to operate to this very day.
The legal case against Leong Sze Hian is one of many examples of how the law can be used to put pressure on ordinary Singaporeans.
There would be no case to answer if current UK law were to be applied.
Famously Singapore has still failed to update it’s rape laws and to this very day it is NOT a criminal act for a wife to be raped by her husband.
Singapore inherited that law from the British too, yet the UK modernized their laws 3 decades ago. The UN have asked Singapore to amend this law and still Singapore has not done so.
Wikipedia: The first fully reported case in which libel is affirmed generally to be punishable at common law was tried during the reign of James I (1603-1625) Scholars frequently attribute strict English defamation law to James I’s outlawing of dueling.
On the year of Singapore’s 200 year old birthday (19/02/1819) it may be a great time to review and modernise the laws it has stubbornly held onto which no longer protect or serve the Singaporean people.