In this passage, the original manuscript is extant for Korihor’s statement after the first occurrence of “behold I say”. At this point in 𝓞, Oliver Cowdery initially wrote there, a possible contraction for they are (that is, they’re). From a textual point of view, the contraction they’re is highly unlikely since the Book of Mormon systematically avoids contractions of words. Yet Oliver did not correct his initial there in 𝓞 to they are. Instead, he overwrote the r of there with an s, giving “these are in bondage”. The correction was virtually immediate since there was no change in the level of ink flow for the overwriting. Mix-ups between there and these are fairly common in the manuscripts; for a list of examples, see under Alma 13:16.
When Oliver Cowdery came to copy this passage from 𝓞 into 𝓟, he again initially wrote there; but this time he corrected the there to they, giving “they are in bondage”. He was perhaps influenced by the use of they in the latter part of the verse: “behold I say that ye do not know that they are true”. In any event, all the printed editions have followed the final manuscript change, the subject pronoun they.
Elsewhere in the text, there are numerous occurrences of these are, although the majority of them are followed by a predicate nominative noun phrase postmodified by a restrictive relative clause (as in Helaman 1:3: “now these are their names who did contend for the judgment seat”). But in a few cases, we have examples similar to the original usage here in Alma 30:24, where these refers to a recently identified plural noun phrase:
In these examples, each instance of these is immediately preceded by a reference to the speaker, just like here in Alma 30:24 (“behold I say : these are in bondage”):
It is also worth noting that the use of the demonstrative these is appropriate in Alma 30:24 since the preceding text has the demonstrative this (“ye say that this people is a free people / but I say : these are in bondage”). The critical text will therefore restore the corrected reading in 𝓞.
Summary: Restore the original demonstrative these in Alma 30:24, the corrected reading of the original manuscript: “behold I say : these are in bondage”.