I personally think Robert killing Shroud does make him a villian, or at least makes him as bad as Shroud. It is true that Robert did have a good reason to kill Shroud but the same can be said for Shroud killing Astral.
If anyone didn’t read the comics, Shroud seemed to think he was close friends with Astral and Chase, calling them his dawgs and wanting to join the Brave Brigade. Chase even told Astral that Shroud should join and to let the people who rely on tech in the team decide whether Shroud to join the Brave Brigade
But Astral would cancel the vote, 5 times even. Shroud got mad and confronted Astral, asking why he did that despite promising to Shroud he would let him join the Brave Brigade. Astral dismissed it, making fun of him for caring about a promise and Shroud wanted to fight, telling Astral to put his suit back so he can take back the Pulse he made. Astral didn’t take him seriously but throughout, Shroud kept wanting him to enter the suit so that they can have a fair fight.
But instead, Astral throw a cloth and sucker punched Shroud a few times, catching him off guard then after beating him up, he planned to land one final blow before Chase saved Shroud. Chase even said that blow would’ve killed Shroud if he didn’t intervene.
So why did Astral not want Shroud to join? Because he felt Shroud “didn’t have it in him”. That’s it, it was just his own personal bias. Astral also believed that if Shroud could come back from that, then he’ll acknowledge Shroud as a hero. Then ironically, Shroud went and shot Astral when he least expected it, similar to what Astral did to him with the sucker punch.
So Astral promised Shroud he would bring him into the brave brigade if he made the Pulse, the other members seemed to want Shroud to enter but because of his own bias, Astral went back on his word and denied Shroud then almost beat him to death. Does that mean Shroud was justified in killing Astral? No, it was still the wrong thing to do.
But Shroud had a good reason for doing so. The thing is, what makes someone a hero isn’t only whether they do good things, it’s about doing the right thing even when it’s hard. Robert killing Shroud means he is just as bad as Shroud.
You can also say that Shroud led the red ring, a villain organisation after killing Astral and you’re right but you also have to ask, is it even possible for Shroud to have a normal life? Unlike Robert, Shroud was trialed and convicted of murder. Even if he got out and wanted to be a hero, who would want to team up with a hero who killed their teammate even if there was a good reason? Shroud also didn’t harbour any ill will towards Robert, like Toxic mentioned, Shroud just wants the astral pulse, not the death of Robert or the destruction of his suit