I think the most proper thing for the jet should be to destroy itself. In a war enviornment I would not like my enemy to gain intel about my military jets.
A heavy object moving fast has a shocking amount of energy. When such an object impacts the ground, all that energy has to go somewhere.
This is a standard technique for quick and secure data wipes, particularly on e.g. modern SSD drives where a traditional wipe might be incomplete due to wear leveling algorithms.
Even if mechanical, warplanes get combat damage, and having a system like that could make a difference between survivable and sure death.