In the printer’s manuscript, the word thus is supralinearly inserted with heavier and darker ink flow. The quill is considerably duller than the one Oliver Cowdery used to write the text here in 𝓟. Based on multispectral imaging of the added thus, the ink for this correction appears to be different than the ink Joseph Smith used to edit this page of 𝓟 for the 1837 edition. There are two nearby corrections on this page of 𝓟 that were made by this unknown hand (it may be the 1830 compositor)—namely, the crossout in the previous line of “that he” (see the discussion above) and an attempt to correct the spelling Priests crafts three lines below (where the corrector ended up accidentally deleting the s in Priests that came before the t rather than after). These three corrections are found in lines 15, 16, and 19 on page 66 of 𝓟.
Like the deletion of “that he” earlier in this verse, the insertion of the thus appears to be due to editing. Originally, the clause “for it behooveth our God” is parenthetical and states that God considered it necessary that the Savior be crucified. The thus implies that somehow the crucifixion itself caused God to consider it necessary. Usage elsewhere involving behooveth shows that the thus is not required. Earlier in this two-part discourse, Jacob explains why the crucifixion was necessary:
In 2 Nephi 10:3, Jacob reminds his listeners that the Lord himself requires the crucifixion. Even though the Jews in Jerusalem will crucify the Savior, the atonement is necessary and ordained by God himself. The insertion of the thus in 2 Nephi 10:3 is totally gratuitous and unnecessary.
One possible reason for adding the thus is that the reader expects the phrase “it behooveth X” to be followed by a that-clause. But here in 2 Nephi 10:3, there is no following that-clause, and so it appears that the clause “for it behooveth our God” is stranded. And indeed it is: the clause is parenthetical.
Elsewhere there are two other examples in the text of “it behooveth”:
In both these examples, there is a logical connection with the previous clause, thus the connectors yea and for thus.
There are two examples of the verb behoove in the King James Bible, and both also refer to the atonement:
In both of these cases, there is a logical relationship with the preceding clause, thus the use of the connectors and thus and wherefore. But in 2 Nephi 10:3, the clause involving behoove is parenthetical and should not be connected by thus. The clause should probably be punctuated with surrounding dashes in order to clearly show its parenthetical nature.
Summary: Remove in 2 Nephi 10:3 the intrusive thus that the 1830 compositor or some other corrector added; the original clause (“for it behooveth our God”) is parenthetical and should not be directly connected with the preceding clause by the use of thus.