Also, he believed that Joseph had been killed, not kidnapped.
Malthus:
I do not believe that’s true. The brothers short-circuited Jacob’s ability to respond, and he disagreed with how they went about it, but I do not think that left to his own devices, Jacob was willing to let Dinah stay with Shechem. At the very least, the Torah to this point demonstrates that there was a standing taboo in Abraham’s and Isaac’s family against intermarrying with the Canaanites.
This makes sense to me, too. The part about Dinah meaning “justice” fits too well. The text presents both arguments and does not really decide at this point.
My only qualm is how you said this is used, at least in part, to justify why Judah is the one who gets his father’s main inheritance.
These weren’t any ordinary Caananites though - they were willing to become circumcised and to “live as one people” with Jacob’s tribe. In effect, they were offering to merge tribes - on the conditions imposed by Jacob’s sons. An argument could be made that, by fulfilling the outward covenant of circumcision, they were in effect offering to become Israelites (obviously there is more to being Israelite than circumcision, but it is reasonable to suppose that the Caananites did not know this - after all, circumcision was the only thing the sons of Jacob demanded of them to live as “one people”).
There is nothing in the text indicating that Jacob raised any objections to this. His only recorded statement is his anger (and fear) over the deceit practiced by his sons - not that they had made a bad deal in the first place. If he’d had objections, why didn’t he raise any before the deal was finalized? He was clearly capable of rebuking his sons, as he does exactly that after the massacre.
Malthus:
The conditions were imposed by his sons (and that, for the purpose of duplicity, never meaning to allow them to intermarry) - not by Jacob himself.
In fact, there’s no indication in the text that Jacob was even present when the brothers made their “offer” to Shechem. Hamor and Shechem presented their request to both Jacob and his sons together, but the response was from the sons (i.e., Dinah’s brothers) alone.
To my mind, the natural read of that scene is that it occurred at the same time - that is, the two Caananites made their offer and recieved Jacob’s son’s counter-offer at the same meeting - with Jacob present.
In any event, Jacob could hardly have been ignorant of it, as there were three days between the men of the town circumcising themselves and the massacre. Surely Jacob must have wondered what was going on in those three days, at least to inquire what became of his daughter - yet there is no indication he complained about the deal.