There is plenty of blame to go around and a lot of people have things to answer for in the wake of Avengers: Infinity War and Thanos' universe-balancing. The most notable mistake that lead to the deaths of countless lives was when Spider-Man and Iron Man almost had Thanos' Infinity Gauntlet removed, only for Star-Lord to, in a grief-stricken rage over Gamora's death, attack the Mad Titan and thus enable his eventual victory and genocide. To some this is unforgivable, but Star-Lord has his apologists... I mean defenders. Among them Chris Pratt's Jurassic World: Fallen Kingdom co-star, Bryce Dallas Howard, who defended Star-Lord's mistake in Infinity War, saying:
He's the most human character. He's half human and that spoke to his humanity in that moment. I think it is important that everyone realize that it was Thanos who did it. It was Thanos.
While Peter Quill should still be on the hook for manslaughter or accessory to genocide, Bryce Dallas Howard makes a good point that ultimately it was Thanos that snapped all that life out of existence. All the mistakes made in the efforts to thwart the Mad Titan, from Peter Quill's rage to Thor's misplaced axe strike, all of them are merely errors in judgment, not evil acts. Focusing too much on the mistakes of your friends can make you lose sight of the true enemy, Thanos.
Chris Pratt's Star-Lord is a human with all the complicated flaws that come with that. As Bryce Dallas Howard told Comicbook.com, that moment speaks to Star-Lord's humanity. Grieving for someone you love and wanting vengeance for their loss is completely understandable. Who among us can say we wouldn't do the same? It's just a shame that Star-Lord's rage blinded him to the fact that the greater revenge would have been to complete the plan and take the gauntlet, thus denying Thanos of his life's ambition. Then he could have killed him and it would have been all the sweeter.
Bryce Dallas Howard is a good advocate for Chris Pratt's Star-Lord, but she herself is no stranger to playing character's making tough decisions. In Jurassic World: Fallen Kingdom, her character, Claire Dearing, also had to make a much-debated choice. In that film, she ignored her heart and did what she reasoned was best and opted to let the dinosaurs die and go extinct once more. But Maisie pushed the button and freed them, thus crossing the Rubicon and ensuring that the world will never be the same. So even though she made the 'right' decision, the dinosaurs got out anyways. Likewise, even if Peter Quill hadn't done what he did, Thanos may have still won in the end.
Whether Peter Quill will get a chance to atone for this mistake and take a more calculated bit of revenge on Thanos remains to be seen. He, along with the rest of the Guardians, sans Rocket and Nebula, are all cosmic dust at the moment. But hopefully with the help of Captain Marvel, they can live to fight another day.