Given that NEMESIS’s Signal was intended to awaken HADES, the one Subordinate Function that could control GAIA, a true super intelligent AI, I think that given the indented function of HADES was to reverse an unsuccessful attempt to create a new biosphere and Tida could have been giving half truths, HADES called NENSIS “masters”, a Dead Earth would slow but not stop FZ, and possibly GAIA’s thoughts in her final message could have simply been the most obvious action HADES could take or her being unaware of it’s full altered purpose, if GAIA was unable to initiate self destruction,
Combined with the information that NEMESIS gave HADES about how to defeat ZF shields, something that if the Signal sole function was to awaken it and destroy the world would have not been needed, and to reverse terraforming HADES would most likely need the machines of ZD to do it correctly, with it’s actions with the Eclipse being HADES next best option to fulfill its altered purpose, maybe HADES was intended for a different purpose that was thrown away when GAIA self destructed,
With the fact that short of the depleted supply of, humans, animals and plant seeds to recreate the world after HADES was activated, with ZD facilities after the destruction of the biosphere in a normal manner would still be operational, with such resources being available within the Odyssey, given that it seems that FZ never created additional humans or other forms of life and lived fully in VR when arriving at their Colony, and NEMESIS having all the memories of FZ would thinking logically be able to understand such a situation,
With the possibility that it could have sent the Signal to HADES in the possibility that, given its control over the Terraforming System and potentially not having the same higher level directives that would limit its interactions with the tribal generation of humans and full control over the entire machines of ZD, that NEMESIS might have intended to have HADES turn Earth into a planet sized trap for FZ, letting them come and with the seemingly primitive nature of humanity use the counter to their shields to destroy them after disabling the Odyssey, at least or another way to harm FZ, maybe going full Terminator or The Matrix Nightmare version,
With the potential that given that the other Subordinate Functions where unwittingly turned into full AI’s, they could have either fought with or against HADES for control over ZD, with or against a restrained GAIA, as a potential unintended consequence of NEMESIS Signal as in the events of the games,