The question here is whether the subordinate conjunction that is missing after the second expedient; in other words, perhaps the original text read “or it is expedient that there should be a stop to the shedding of blood”. The original manuscript is very clear here; there is no that written either inline or supralinearly.
Elsewhere in the text, there are 48 occurrences of expedient complemented by a full finite clause, and in each case that precedes the clause. In fact, earlier in this verse, we have one of these examples: “therefore it is expedient that there should be a great and last sacrifice”. But the second instance of expedient in this passage is unique in that the clause itself begins with the conjunction or (“or it is expedient there shall be a stop to the shedding of blood”). The use of the or corrects the previous clause, left unfinished, in which Alma says “and then shall there be”; at this point Alma decides to correct himself by adding “or it is expedient there should be”. The previous incomplete clause has no that, and it is probably because of parallelism with that clause that the following corrective or-clause also lacks the expected that after expedient. The critical text will here maintain the reading of the original manuscript in Alma 34:13 since the lack of that after the second expedient does work.
Summary: Even though Alma 34:13 has the only example in the text where that does not connect expedient with a following finite clause, the use of the corrective or in this verse creates a strong parallelism with the preceding conjoined clause, which has no that (“and then shall there be or it is expedient there should be a stop to the shedding of blood”).