Perhaps Gandalf feared the power the ring would have over the eagles. Not during the trip, as discussed in the article, but at the moment when it needs to be destroyed. If the eagle changed its mind at that point, there would be nothing they could do about it.
He did not even trust himself with the ring. The ring corrupting a powerful being would be far more devastating than the corruption of a hobbit or man so perhaps he thought that the less involved such beings were in the actual destruction the better.
It's a pity Tolkien isn't around because he must have thought that the reason was trivial enough not to warrant an explanation.
It seems that the more powerful the being, the more likely the ring is to corrupt them. I think that the worry would not be that the ring would corrupt the eagles, but their masters, the Valar.
He did not even trust himself with the ring. The ring corrupting a powerful being would be far more devastating than the corruption of a hobbit or man so perhaps he thought that the less involved such beings were in the actual destruction the better.
It's a pity Tolkien isn't around because he must have thought that the reason was trivial enough not to warrant an explanation.