I am the author of the web page in question. The claim you're making is that Manwë put some kind of limitation on the eagles: some types of help are acceptable, but other types are prohibited. As far as I am aware, the text does not say this anywhere. The argument you make is indirect: it is based on the types of help which we observe the eagles actually giving. If Manwë did put some sort of general limitation on the forms of help which eagles are permitted to give, how exactly could that limitation be formulated? We know that the eagles can carry the ringbearer (they carry Bilbo at a time when he is in possession of the Ring). We also know that they will fly into Mordor. The limitation by Manwë would somehow have to permit those things individually but rule out doing these two things at the same time. Since there is no direct evidence in the text that Manwë enacted any such limitation, I think that the simpler account is that no such limitation exists.
Thanks a bunch for stopping by! Yeah, most of my argument is based around circumstance. I think the foremost evidence that Manwe enacted some sort of interdict (something I took for granted in my last post and thus didn't bother to address) is that the eagles don't fight in every battle in the entire series, which I think you would expect from them as one of the foremost forces for good. This is, of course, just as indirect as everything I said. I'm certain there's no direct evidence in Silmarillion, LotR, or Hobbit, and it's been a bit too long since Unfinished Tales etc. -- so just a possible counter to point 8, one that helps alleviate the sadness that would come with knowing Tolkien left such a large plothole. Thanks again for the post.
Interesting discussion, it seems we are working with a limited amount of data, which is a shame. Although I've not spent every day of my life thinking of LoTR, I've probably thought about it more than most so I appreciate the attempt at an answer but will likely remain a fly on the wall for this one. Also, it appears that the author has stopped by -thank you for inviting them, always a treat.
[If you, like me, have been thinking about Lord of the Rings in some way every day for the majority of your life, please read!] Point 8 is where I think he makes his most assailable argument. He acknowledges that the eagles are direct representatives of Manwe, but points out that they clearly aren't constrained by Manwe's laissez faire policy when it comes to Middle-earth post-Flight of the Noldor. He lists several examples of Third Age intervention on the part of the eagles. However, most if not all of those examples are much less direct that what he suggests be done with the ring. Most show the eagles saving a person or group of people. The two times they interfere more directly (at the Battle of Five Armies, and at the last battle at the Black Gate), it is never stated in the text to my satisfaction exactly what level of interference they gave. I have always extrapolated that at the end of the Hobbit, they mostly used their air presence to dismay and distract the goblins while the dwarves and elves rallied (I think there may be mention of dislodging goblins from high places where they have seized a battlefield advantage.) This is relatively indirect and could easily fit under any mandate Manwe had issued regarding interference in the Third Age (perhaps only a couple of times, or only when absolutely vital). I will also note that many of the peripheral characterizations in the Hobbit don't fit into the canon of the Lord of the Rings as well as Tolkien would have liked, because the Hobbit was written for a different purpose and at a different time than much of his other work. I'm not sure that we can let the eagles' actions at the Battle of Five Armies stand as direct evidence as to what their actions could potentially have been vis a vis the Fellowship. Secondly, at the end of Return of the King, I felt that a) the eagles were present mostly to defy the Nazgul, and b) that there was a sort of "all bets are off" feel -- any interdict could feasibly have no longer applied. That's flimsy; I prefer 'a' to 'b' but felt like mentioning both. In any case, once again they arrived as a character whose point of view we were following departed, and we have little textual evidence of what actually happened. I would further posit that under the hypothesis that Manwe still directly controls the eagles to an extent, he has most likely issued orders to them to help in circumspect ways if at all -- and that if indeed there is a chance the ring can be destroyed in a way that doesn't (overtly) involve Manwe's emissaries in Middle-earth, then let it be done that way. Of the main characters, Gandalf and perhaps Galadriel would be most likely to assume/understand this.