Originally this passage ended in a direct quote (“which hath been sent from the Nephites to torment us”). There have been two separate emendations in this passage to change the direct quote into an indirect one. First, in his editing for the 1837 edition, Joseph Smith converted the presenttense hath to the past-tense had. And second, the 1920 LDS edition replaced the first-person us with the third-person them (the RLDS text has retained the original us but not the hath since Joseph marked only the change to had in 𝓟). Thus the current LDS text is fully consistent with the surrounding indirect quotes from the speech of others in the crowd (the emended line is marked with an arrow):
In this case, quote marks would help the reader deal with the original direct quote in the middle of this sequence of indirect quotes:
There is one clear case where the text intentionally shifts from a first-person direct quote to a third-person description; this rather striking shift in the narrative is found in the middle of Helaman’s letter to Moroni as recorded in Alma 56–58. For discussion of this example, see under Alma 56:52–53. Here in Alma 19:26 we also seem to have an intentional shift in person and tense, but only within part of a sentence. Even so, the critical text will restore the partial direct quote here.
There is one additional possibility that should be considered here. Perhaps in the original text for Alma 19:26, the direct quote actually began earlier in the sentence:
It should be pointed out here that the Book of Mormon text allows direct quotes to follow saying that, as in the following example:
(For additional examples, see the discussion under 1 Nephi 7:1.) Thus one could argue that in Alma 19:26 the direct quote began immediately after saying that and that an original is was changed to was (marked below with an arrow) because of the many surrounding instances of “X said that he/Ammon was … ” in the statements made by the crowd:
Clearly, it would be much easier for an original is to have been changed to was in this passage than to have both an original had changed to hath and an original them changed to us. But the earliest text in Alma 19:26, with its mixed use of tense and person, will work. The critical text will accept that reading, thus interpreting the sentence as switching midstream from an indirect quote to a direct one: “but others rebuked them all / saying that he was a monster which hath been sent from the Nephites to torment us”. Nonetheless, the possibility remains that the past-tense was in this sentence is an error for a present-tense is.
Summary: Restore in Alma 19:26 the original use of a partial direct quote in the middle of a sequence of indirect quotes: “he was a monster which hath been sent from the Nephites to torment us”; it is possible that the past-tense was in this sentence is an error for the present-tense is.