“The Northern path is ruled out because it flies into to much radar coverage not to be seen, leaving only the southern path.”
There was an article in the Times of India a couple weeks back that said that India’s defense radar was inoperative along the eastern coast. This basically leaves Bangladesh or Myanmar, and we have heard zip about their radar capabilities or lack of capabilities. So the northern route was ruled out because of an assumption. Of course, everything that is publically known has layer upon layer of assumptions. Even the doppler model taking it south is based on assumptions according to the people who devised it.
The Doppler model would be unable furnish any hints to distinguish between the northern route and the southern route. Knowledge of prevailing winds might be a discriminate, I do not know.
I question the effectiveness of Southern Asian military radar networks, myself. Except for India, I doubt if there’s much there, and the Indians are bowing out, it appears.