I'm sure there are political considerations.

India of late has a capricious regulation problem which makes it difficult for tech firms to have predictability.

And everyone already knows you can get decent quality manufacturing done in Vietnam. India would like to be considered in that same group.

Therefore it's in Apple's interest to present India with the opportunity to demonstrate that capability, while giving Apple a measure of leverage in cases where India's government is considering outlawing encryption or unmoderated forums or the shift key or whatever they think will make people stop complaining about them today.