Since no physical bit of Nomad looks like the picture of the original Nomad, we might well argue that nothing but the soul of the onboard AI survived the merger. What we see might well be Tan Ru and nothing but Tan Ru, packing its original alien weapons and shields.
It's just a bit odd that we never ran into the makers of Tan Ru. If it collided with (rammed? otherwise intercepted?) a primitive Earth probe, this probably happened fairly close to Earth. Did Tan Ru come from afar? But even this then suggests it had significant propulsive capabilities, and its makers might be flying around in ships likewise propelled, posing a major threat.
Then again, the very idea of berserkers that sterilize whole solar systems is that the makers don't need to leave home in order to make the galaxy a safer place for themselves.
Then again again, Nomad only seems to have scored one proper kill that we know of. Even the Doomsday Machine did much better in the time allotted. Is this because Tan Ru is in fact incredibly slow? Or is it picky with what it kills? Not proper berserker behavior, that latter one - the idea is to waste no time fighting dangerous adversaries when it's so much easier to just kill everybody wholesale before they manage to become dangerous. And then we have to decide why Tan Ru chose Maluria...
Timo Saloniemi
It is possible that the original makers of
Tan Ru were not life as we known it but life as we definitely don't know it. Possibly they lived in temperatures much higher or lower than Earth lifeforms & thus had completely different biochemestries than Earth lifeforms.
They might live on rogue planets in interstellar space and Nomad/
Tan Ru might have only visited such planets and judged their lifeforms perfect or not until some strange quirk of fate led it to investigate the planets huddling close to a star, the one in the Malurian system. Thus the makers of
Tan Ru might not interact much with lifeforms that live at our temperatures.
I have speculated that Tholians might live at temperatures much lower than Earth lifeforms, while other fans have speculated that Tholians live at temperatures much higher than Earth lifeforms. A Tholian representative was apparently in a room with humans and others according to "Homefront", but might have been wearing an environmental suit like Nadrek of Palain Seven. And "In a Mirror Darkly" described Tholians as living in very hot environments.
So possibly makers of
Tan Ru might be Tholians or similar beings.
Possibly the makers of
Tan Ru were cybernetic beings who had moved away from the planets full of organic lifeforms who had originally created them to regions more suitable for machines. Perhaps Nomad/
Tan Ru only investigated such astronomical bodies, or space stations, or whatever, where machines lived but there were no organic lifeforms, and so judged all the beings it encountered to be perfect. Until chance circumstances led it to the Malurian system.
Thus the makers of
Tan Ru might have been beings of the Machine Planet in TMP, or Borg, though since those are small universe type speculations perhaps the makers of
Tan Ru might be merely similar to beings of the Machine Planet in TMP, or Borg.
If
Tan Ru was built to be a doomsday weapon, perhaps the first beings it judged to be imperfect and sterilized were its creators, explaining why they were never encountered in any episode. Creating a doomsday weapon could be considered to be a very illogical and imperfect decision. Could they have been the creators of the Planet Eater in "The Doomsday machine" or maybe their opponents in the same war? Maybe, but that is also a small universe type idea.
Either Nomad had been destroying planets outside of Federation space so the crew never got to hear of them or Nomad and Tan-Ru had only recently completed repairs! We don't know how long ago the two probes encountered each other after Nomad's damages in the meteor storm!
JB
Good idea.