The lions can learn. Eventually, the flashing lights will become common enough the lions no longer fear them. Then they won't be safe walking around with the flashlights either.
A rancher in Colorado used the same system to stop wolves from raiding his sheep herd at night. The EPA, Co Wildlife and Dept of the Interior at the urging of PETA stopped the practice, imprisoned and fined the rancher for violating endangered species acts and using cruel and inhuman devices to blind wolves during their hunt.
He could always hook up sensor connected to an automatic weapon.