@Tokenbird
Fascinating that the reported flight track appear to follow the FIR boundaries. Would be great to overlay the track on your FIR map. The U turn when a/c touched the Indonesian FIR could be consistent with evasion. This would make sense if pilot thought he might have a tail/intercept/monitored after his crossing of the peninsula. If there was a low altitude over the Peninsula and Straits it would also be consistent with radar evasion. I think we have to give evasion a high probability given the known/likely data points.