>>115188547>the entire clusterfuck that was Angron's discoveryThe Emperor offered help, and Angron told him to eat a dick. Angron didn't want to be helped by the Emperor. He didn't want a Legion teleporting in to help him, he didn't want the Emperor or the Custodes to help him. He knew that he was going into a battle that he would not survive, and he was perfectly fine with that. He wanted to die fighting beside his fellow gladiators.
It wasn't a rebellion or an overthrow, it was suicide by cop.
If you want to blame anybody in particular, blame Guilliman for bringing Nuceria into peaceful compliance with Greater Ultramar without realising an undiscovered Angron was there about to rebel against the exact people Guilliman was making a treaty with. That said, even Guilliman can't be judged on something he has no idea about. The Emperor came running as soon as he realised, but it was too late. So he saved Angron in the hopes that he could fix the Nails problem later, but realised that it was impossible to remove them without killing him. At which point, his choices were "put him in stasis forever", "euthanise him", or "give him a Legion and let him go out fighting in the few years he has left".
The Emperor should have taken door number 2. Instead he gave Angron a Legion, and Angron spent the rest of the Crusade attempting to find something capable of killing him once and for all. Then he turned traitor, and Lorgar, realising that Chaos needed something capable of fighting Sanguinius, arranged for the trickery that forcibly ascended Angron to a Daemon Prince of Khorne. Which then meant that Angron had only a couple moments of freedom from the Nails, before Khorne's rage filled him and he was a slave for all eternity. Not even death will end Angron's suffering now.
There are a lot of people at fault for Angron, really. The Emperor was just one of them. Lorgar, Guilliman, and Horus are three others.