Because they store energy
When they die, they leave an organ with remaining stored energy. This presents a huge opportunity. Possibly the organ can be used as a super battery, charging and discharging with negligible degradation. We see the creature use it to great extend. It can do so in enormousdischarges great amounts of energy if needed (see. Just look at the light jump) and likely store. Possibly it at incredible speedscan store rapidly as well (see the, as it stops after a light jump. IfEither it uses more of it's stored energy, or it is like a dynamo, stealing momentum for again stored energy. As it stops itselfquickly, it needsis an impressive battery that can do this. That, as well as the possibility to either expend newnot expand but gain energy or somehow remove energy from itself and storing that energyin space when stopping.) They will hunt this creature for the scientific possibilities alone.
Other scientific discoveries would include how it can survive on practically sunlight alone and such. People would kill it to extinction for the research opportunity, even knowing that killing the last one might not allow them to get more research done.