Double-knock skepticism

A reader who is an ornithologist emailed me these thoughts:
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John Fitzpatrick of Cornell has not acknowledged publicly that the Pileated Woodpecker (PIWO) gives a double knock. This behavior has been known for many years; for example, here's a snippet from Short's 1982 monograph (p. 419) regarding "demonstration tapping" in the Pileated. My additional comments are in brackets below:

"This form may occur as a double tap, akin to the drum taps that are characteristic of various species of Campephilus; such a double tap may be associated with copulation or may occur at a prospective nest site (Kilham, 1959d, p. 381). Such demonstration tapping is known in D. javensis and D. martius [a reference to the congeneric White-bellied and Black Woodpeckers]. Drumming takes place all year, but especially marks the prebreeding period, for example, in December and January [when CLO's ARU cuts were obtained] in Maryland (Kilham, 1959d). Bent (1939, p. 175) cites Sutton as indicating that a drumming burst may be followed by three distinct blows, thus resembling drum taps of Campephilus, but Hoyt (1957) did not this these are typical, nor do I."

.... Nothing in the ARU cuts eliminates PIWO or, for that matter, a Red-bellied Woodpecker or Yellow-bellied Sapsucker, both of which "double knock" as well.
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