I can address the notion of Neihart being trained by Moll, although I can't address the remainder of the article as I don't have it.
"Trained?" I would doubt it, although discussion of any relationship between the two men is speculation.
(1) Neihart was already 20-21 years old by the time Moll arrived in Allentown.
(2) Neihart was only once, prior to the Revolution, noted as anything other than a "yeoman." A single 1767 assessment or township list (on file at HSP) noted him as a 'smith,' but in all other documents prior to the 1780s he was noted as a yeoman.
(3) His work does not look like the signed work of John Moll; I am not merely indicating decoration, as he (Neihart) had a VERY distinctive decorative style that is easily identifiable. Architecturally, Neihart favored a longer and lower cheekpiece in his stocking which is very different than the typical high, short Moll/Oerter/Rupp style.
There are one or two later "Allentown" rifles which have been pictured in some texts ca. 1960s- 1980s and attributed to Neihart, although they are unsigned. It is my *opinion,* based upon a long and focused study of NH County arms, that they were definitely not made by Peter Neihart. I believe these old attributions have muddied the water a bit. While he may have possibly adopted a more typical Moll/Rupp form of stocking later in the early Federal period (and I emphasize 'may have'), his earliest post-War i.e. 1780s-early 1790s era work is very distinctive and different than that of John Moll (who was dead by 1794) and Herman Rupp's dated 1793 rifle, so we are comparing very contemporary pieces.