Singapore's economic policies are complicated and often misdirecting. I'll break down the misconceptions.
The primary purpose of CPF is not a pension scheme. It is structured as a massive forced bond purchase scheme by citizens. Financially what happens is the 37% of citizen income buys a long term bond (till retirement age, on average decades) at rock bottom interest rates (it's pegged to the overnight rate or a minimum of 2.6%). The returns are specifically decoupled from the real long term returns. This has historical roots in the government needing vast capital financing. They make enormous amounts of the delta between the short term interest rate and long term capital gains. Singapore has no oil or natural resources, but it's sovereign wealth fund has AUM in the regions of countries like Norway which do for this reason. It is not a shock absorber like the article suggests. The withdrawal terms are strict - housing, a significant medical expense and retirement are the only real ways to get money out of it.
"Trying to keep people employed" is a goal, not a policy. In fact the Singapore government maintains a large worker supply through immigration. The foreign worker population, ~30%. The main goal of the government is to maximize the absolute number of people working.
The reason it raising the retirement age is effective in workforce participation is because most people have no choice. Retirement only pays out after the age. The working life of an average Singaporean has seen 37% gone to CPF, maybe another 10% to income taxes, another 5% to GST, road tax, property tax, etc. After all this there's the astronomical cost of living. This is also intentional, to raise the number of employees.