JMB,
No articles are being quoted. His biography mentions this feat, supported by a newspaper article with a similar story.
There is NO doubt that Willie's specialties were playing quickly (has documented run of 125 in 18 minutes) and playing close position. He routinely during his exhibitions would make a show of pointing to a dime sized spot, and park whitey right there; shot after shot - it was part of the "wow factor" of his exhibitions that he took great pains to develop. The guys that watched him play in his prime say no modern player tries for such close position on a routine basis, though some of the great one-pocket players are probably capable of similar feats. This description is from guys that played with him 8 hours a day for 2 or 3 years.
Further, it was this type of pinpoint position play that allowed (according to a description I heard from Irving Crane) Willie to continuously seek to park whitey right in the center of a semi-disturbed pack, and then just shoot his way out, moving the cue ball a precise inch or two at a time. Crane said this type of play was only possible for Mosconi, and that Irving and the rest of his contemporaries preferred to get to center table and pick off balls from the periphery.
The only player I have personally seen play this style of pool was Danny DiLiberto - it is an art form. If you have never seen Danny play straight pool, then you can have no idea what I'm talking about from my feeble description. I've seen it, and I'm not sure I believe it. I think we will just have to respectfully agree to disagree.
P.S. - that "man landing on the moon" stuff is a real crock - couldn't have happened.