As any sixth grade student could point out, the presence of a simile is not mutually exclusive with and actual description. The shadow stretched out LIKE "two vast wings". So what was it a shadow of, you ask? Well, could be two wings. It never says the wings weren't there.

As for the second passage, we are dealing with a non-corporeal being. It drew itself up to great height and spread out it's wings. We don't even know what the body it drew up looked like. Since the Balrog is apparently a being of shadow and fire, why can't it have wings comprised of shadow?

I certainly wouldn't say the conclusions are empty, since you didn't appear to read any of the citations in the article. Are you a lawyer or something? You can't take certain parts of a description, ignore other parts, and come to a valid conclusion in contradiction with the parts you discarded. Seems fair to me. The HoME books do a great deal of explaining how Tolkien put together his world. When you say:

"The Balrog of Moria did not have wings. If those of the First Age did, what of it? By your own admission, such references are non-canonical."

You actually invert his argument. Balrogs from the early texts (Book of Lost Tales) did not have wings. There with 1,000+ of them, and they were mounted (Hence, they followed in Glaurung's train, a phrase used in The Silmarillion).

The later Balrogs, including the resident of Moria, seem to have had wings, since they flew over Hithlum with winged speed. Makes sense to me.

I don't know why it is bad for Michael to offer a link to a page that explains HIS argument so he doesn't have to keep re-typing it. You know, like I just did. Is it somehow more valid to send you to a page that has someone else's argument to convince you?