Yes the tank turrets were placed in certain areas for direct firing.With a weight of 42 kilos Nag is not exactly man portable. But I do remember reading some time back that at many positions IA has moved in the retired Vijayanta Tanks to be used as static turrets. If a tank could be moved to some positions I guess BMPs can go in as well.
But that operation took place over a long period of time. I am just doubting if a couple of Namica can zip through the mountains from one BOP to another. I am not seeing a huge advantage to using Nag missiles over Konkurs/Milan to hit a stationary target! In fact you don't even need the new version of Milans (AT, with the extended nose) as the BOPs don't have reactive armors!
Also to note is that no other source is reporting the use of Nag missiles.
We'll have to wait and see what the full extent of the truth is!