As yet, I can only place these two in the same room at the same time at Mark Twain’s 67th birthday party hosted by George Harvey. Subsequently, Pyle was invited to the 70th birthday - Harvey’s even larger publicity stunt, held on December 5, 1905 - but he couldn’t attend. In sending his regrets to Clemens, Pyle wrote that “it is not often that a fellow craftsman can have it to say that in nearly half a century of work he should never have written any words that were not pure, and kind, and free of malice toward any of his fellow-creatures.”
Reviews of the autobiography, however, make Pyle sound pretty naive - or just hyperbolic and polite. In Slate, for instance, Judith Shulevitz says,
...this volume is punctuated by uncomic riffs - I believe they are meant to be funny - that quickly degenerate into furious rants, usually about former business partners who had grievously cheated Twain. The unvarnished truth about Twain/Clemens turns out to be his unvarnished rage.