I would think that the balloon vehicle has very limited power resources for things like ECM. Communications would be the priority.
Good point. But the unit is not going to live very long anyway once it goes active. It can stay passive on low power until it detects a radar lock, then fire up the power to emitters and detectors and see how long it lives.
Communications would be the priority.
A really good point as well. The comm system probably has a separate power supply with a much longer run time. It needs to report back detector results to a remote station right up to the last millisecond of life.
I would expect to find a directional laser or maser on board for final communications to minimize detection of the transmissions and interference with their ECM. That might be giving their engineers too much credit. But Chinese engineers are pretty smart.
I would love to see the crashed hardware.