The problem is, when looking at something in the sky, it is hard to judge size without a reference point because you can't determine how high it is. It could have been a lot closer to the ground than the witnesses perceived so they assumed it was much larger than it was.
You're right. Have you ever seen our big beautiful moon peeking through the trees - yellow or orange?
Then the same moon small and white high in the sky?
Same size.
Total optical illusion.
If you take a picture of the two moon views - and put one negatives on top of the other, they're exactly the same size. ( In the old days we had "negatives... anyhow you get the idea).