It’s probably just a minor detail, the human eye is very good at adapting and perhaps a few of the moonwalking astronauts looked at the sky away from the high contrast regolith, long enough to adapt and saw some of the brightest stars, while others didn’t. As for the nudge, I suspect it was a warning, simply a heads up between fellow astronauts that poorly chosen words might become annoying conspiracy fodder for decades. They went there, they know it, the idea that their words might be used to argue otherwise is probably not their first thought when describing anything about their time on the lunar surface. To them they are describing the material evidence that we went there, so I wouldn’t be surprised if there was a shared desire to keep each other from making mistakes, likely born from years of training together.
Not saying you're wrong about the eye adapting, but note that Collins was not a moonwalking astronaut. I've considered that this could be some difference between viewing the solar corona from the command module as opposed to the surface. It could also be memory issues. Perhaps they ran so many drills with a simulated solar corona photographing sequence that the guy who stayed in the sky mixed up this experience and the real thing, whereas Armstrong knew what it actually looked like. I've entertained wilder thoughts as well, but on the whole I think there's probably a mundane, down-to-moon explanation for the disagreement and elbow nudge.
