The late Roger Tory Peterson on IBWO behavior

Last night, I re-read parts of "Wild America", by Roger Tory Peterson and James Fisher. Parts of the book mention an unsuccessful ivory-bill (IBWO) search they undertook in 1953.

Peterson writes:
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...We reached the last-known ivory-bills' roost hole just when the bird, or birds (if any) could have been expected to come out, climb to the treetop, preen, stretch, peck wood, and call, before their first morning flight. These morning flights, Tanner found, are usually pretty noisy. Kient-kient-kient, the birds cry, loudly and frequently as they forage...If the roost hole had been in use, we would undoubtedly have heard the bird.
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and later:

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...But I count myself lucky to be one of the small company of living naturalists who has actually seen the ivory-bill. That was in 1941 when I saw the last two females in the Singer Tract. They did not look as much like pileateds as I had expected; with long recurved crests of blackest jet, and gleaming white bills, they seemed unreal birds--downright archaic. It was easy to track them, for as soon as they landed after a flight, they betrayed their location by their curious tooting notes. When they flew, they pitched off on a straight line, like ducks, their wings making a wooden sound. After we had followed them for nearly an hour, they made a long flight and we could not find them again....We wondered, as we took a parting look at its last known haunt, whether the ivory-bill had finally joined the spectral company of the great auk, the Carolina paroquet, and the passenger pigeon.
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Here again, we see that during the last known days of the ivory-bill, it was noisy, conspicuous, and easy to track. Peterson does bring up a specific point that I hadn't yet addressed in the blog: the IBWO wingbeat itself was loud. David Sibley wrote this:
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Wingbeats very noisy, producing a loud, wooden, fluttering sound.
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Cornell's paper doesn't contain any mention of anyone hearing this sound.

So, in summary, regarding the mystery bird that the searchers called "Elvis":

It doesn't look like an IBWO.
As far as we know, anyway. In all those sightings, no one saw the white dorsal stripes, the white neck stripe ending before the bill, the longitudinal black stripe on the white wing underside, or the pale bill itself.

It doesn't sound like an IBWO.
In the Cornell paper, there's no mention of Elvis ever vocalizing during an encounter, and no mention of anyone ever hearing the loud wing noise.

It doesn't act like an IBWO.
Cornell's Elvis was impossibly wary, unlike the last-known IBWOs that were relatively easy to track and closely observe.