Because the Indian Army is just sitting there, hunkered down. While the PLA is continually probing and expanding its operational capabilities in the area. That carries risks.
I doubt it, nothing is done 'solo' in the Army, not even recon. Most likely this guy just got split off from his patrol at night and wandered into enemy territory. Comms don't work well in mountainous terrain, it's easy to lose contact.
There's not much intel to be gained by India from this. They can't torture him or force him to reveal anything besides his serial number. Nor would he know much about operations, and whatever he knows (comms frequencies etc.) would have already been changed by now.
With that said, the PLA's high command is not going to be happy with this. A lot of people are gonna get yelled at.
That said we are not Bahkts. I don’t want to white wash this incident. Like Figaro said, this kind of things shouldn’t have happened twice and there should be improvement in situation awareness for PLA troops in the area. Imagine if there really was war. He would have stumbled into an ambush.
The only silver lining to the fiasco is that it dispels the Indian myth that PLA troops have inadequate clothing for the terrain. You don’t wander around at night in the middle of the winter if you are inadequately dressed and supplied.