No, the "he" is clearly meant to refer to Mark Twain, who was born in 1835, when Haley's Comet paid a visit to Earth. Grammatically speaking, the word "he" refers back to the nearest noun, so it does confuse the reader. The sentence should be revised to read Mark Twain instead of using "he". In fact, I have corrected it, as well as correcting the spelling of Halley's Comet.
