Even the "Mother Tree System" had not determined that Saran was dead... or rather, it had actually already made a determination when Saran was devoured by Russell. However, because of the transmitter on Saran's body, the Mother Tree System immediately detected that "Saran was still alive", thus considering the previous signal a false alarm and immediately corrected itself, stopping Saran's rebirth.
So, Russell had the audacity to impersonate Saran and, on the pretense of a "Chip malfunction", boldly went for a top-tier physical examination.
Even the Elf Director's examination turned up nothing out of the ordinary.
It was then that Russell realized he had indeed seized the identity of "Saran". Unless someone attacked Saran, the Director, in a public setting and caused a fatal injury, his disguise as Saran was now undetectable.
After that, Russell began actively intervening in the board of directors under the identity of Saran.
