We see that Nolan does care about his family and was happy on earth but he let his belief and loyalty to Viltrum override that.
But what if Mark was able to convince Omni Man to stop?
To make it interesting, let’s say this is just when they start to fight and when it gets to the part where Mark says
“ Don’t do this, it’s not too late”
What if Nolan had actually stopped and listened and considered what Mark was saying, and after much convincing, Nolan decided to stop and abandon his mission to stay with his family?
Now I picked this point as it is an interesting crossroads as Nolan:
Hasn’t gone on a massive killing spree of civilians yet, killing thousands of innocent people.
He has however:
Killed the Guardians of the Globe
Killed Immortal( Twice), with the second time everyone seeing
Killed Donald and some of the G.D.A. soldiers
Attempted to kill Cecil
Called Debbie a pet.
Now if he does stop and he and mark go to G.D.A. Headquarters, it all depends on what Cecil does from here.
Does he demand Omni Man surrender with no compromise.
Or would he be willing to compromise if given concessions, such as all the info Nolan has on the Viltrum Empire in exchange for walking free.
If the latter, Cecil is going to have to deal with a massive PR scandal to save Omni man’s image and convince both the public and Immortal when he is revived again that the actions that happened weren’t of Nolan’s own will.
Even then, there is then the Grayson’s family life now that Debbie sees that she was apparently nothing but a pet.
what your speculating upon is explored in the comic later on.
Your referring when mark goes back in time right and stops Nolan from killing the guardians?