When Spork discovers that Miyuki dies he goes into some kind of trance or something and kills everyone he sees, being like that he would be Capable to kill Purple and Red?
When Spork found out that Miyuki died, he was devastated. At the time, he wasn't with her during her trip to the Vort Research Lab where it happened. So he blamed himself for not being there when it happened, he couldn't keep his head up as he ran to seclude himself somewhere on Hobo-13. Rarl Kove was equally devastated but he was the one who tried to reach out for Spork when he suddenly went missing (Sizz Lorr tried to reach out too but he received no answer)
Then Rarl would get a tip that Spork was on Hobo-13 so he went there by himself. Sargeant Hobo 678 was the one who sent the message (to Sizz Lorr but Rarl Kove intercepted it). Spork was completely devastated, went on a hunting spree (to a point the creatures of Hobo-13 are afraid of him) before stopping because he was too tired.
Then Rarl Kove found him and the two would talk in a small base (Hobo 678's old base) and Rarl Kove will tell Spork it wasn't his fault. He'll spill the secret about Miyuki, about her origins, who and what she truly is, the generations she's experienced under the eye of the Control Brains, how they treated her, how they tortured her and others, and how they let it happen.
Rarl Kove said it because it's not Spork's fault, he wanted Spork to know this because Rarl Kove has never told anyone - it was a secret of him, of Miyuki, and of the Control Brains. But then he saw it- the way Spork's expression changed after hearing it. He's seen that silent fury before, and Rarl couldn't do anything when Spork stood up and headed to the door.
"... what are you planning to do?"
"Destroy it all."
Funny enough, this grief and heartbreak is something Commander Spoons experienced too. When she heard Garpu was captured by the Empire and thought Garpu died, Spoon snapped and left no survivors.
Under Tallest Cyanide's reign, she obliterated his entire platoon and left no one standing. Her grief, her heartbreak, her love became a raging inferno inside of her to take down everything and everyone.
And if Spork inherited Spoon's strength, that means he also inherited her grief.
Spork wouldn't kill Red and Purple because they were Elites at the time (students, basically kids in Spork's eyes). They had nothing to do with it.
Spork was focused on the Control Brains first. When he reached them, they knew immediately he was hostile and sent him down to a pit full of mechanical horrors to stall him - knowing it won't keep him down long.
Using the mechanical corpses, Spork ascended to Hell.
He'd have to kill every Control Brain copy too, leaving no physical body left. And if it leads to him killing Irken soldiers, Elites, anyone who stands in his path then so be it. He has nothing to lose.
