the article. The only vaccine they have (China's Sinovac Biotech) hasn't yet been tested and approved for use with the elderly...here is the quote...
"Indonesia, which plans to begin mass inoculations with a vaccine developed by China’s Sinovac Biotech, says it does not have enough data yet of the vaccine’s efficacy on elderly people, as clinical trials underway in the country involves people aged 18-59."
So it's also likely that with 'time being of the essence', they have to cross their fingers and go with what's at hand...btw, the Pfizer and British vaccines won't be available for several more months in Indonesia.
As the article also says 'they'll have to wait and see' if this approach is going to work...later in 2021 we'll all know which path is preferable and use this knowledge for future outbreaks...it's a bit early IMO to start spiking any footballs.