This may be spoilers so don’t read it.
Just reading up on some of the lore for the precursors and flood and found out that the flood would purposely not infect some humans as a way to trick the forerunners into searching for a cure, just for it’s own twisted pleasure. i think theres a novel that explains how johnson escaped the flood in CE and that somehow it could, or would, not infect him. i also remember reading something about how chief had to decide weather or not to report his “immunity” which may have killed him to find and chose not to, so chief probably just spared johnson an early pointless death. i know theres something that says it could also be related johnson time in the orion program but this just seemed really cool to me and thought id share.
Its a bit of a muddy piece of lore.
First Strike had him be immune, but Bungie later made it clear they didn’t like this, which is why the comic exists which just shows he was really cool and skilled and thus didnt get infected.
Now yes, in the Forerunner novels it was confirmed the flood purposely didn’t infect some individuals, which might by the 2nd retcon of this to try and make it make sense.
Effectively early halo lore was more of a mess than people realize. What with crystals manipulating itme, halo locations being carved on rocks, and elites, who love a good fight, and according to the CE manual base their ranks on human kills, somehow weren’t seen by Chief until the battle of reach.
https://www.youtube.com/watch?v=724CsXl357s TL;DR Johnson wasn’t infected by the flood because of his involvement in the orion project. The orion project screwed with his biology in such a way that made it harder for infection forms to gain control of him. That gave him just enough time to rip the flood form off of him and escape, but it doesn’t make him outright immune.
Yeah that was true at some point, but as urbanrocket said earlier, Bungie finnaly decided it wasn’t cannon. It’s hard to follow when the studio change the story they made
It was part of a precursor big plan agaisnt the forerunner at this time. During Halo CE, even if the precursor was still in control of the flood, there was no point to simulate a failed infection with johnson or anyone else