Remember that those retired Singaporean diplomats trained the following generations.
In his writings, Lee Kuan Yew was 80% convinced that one day, China would displace the US military in the Malacca Straits and that Singapore would have to prepare for such a shift.
My guess is that every Singaporean diplomat is familiar with this, as LKY certainly wrote and spoke enough on the topic.
As for those rich elite Singaporeans who prefer China submit to US hegemony, have they never watched the opening scene of Crazy Rich Asians, where the rich Singaporeans face discrimination and racism for being Chinese? Today, you can plainly see the racial dog-whistles from the Republican right-wing.
I would say Singapore should be able to remain neutral in a China-US contest. The vast majority of ASEAN agrees on neutrality, and a combined ASEAN is big enough to resist the USA or China.