Actually, it's not ignorance. Shanek already knows the answers to most of his "questions" because they were already answered in the thread that slingblade was referring to.
No, they weren't. They were whitewashed, asserted, and obfuscated, but they were never answered.
1. Sinclair never claimed that human "meat" was being sold. Sinclair told the story of one man who accidentally fell into the lard rendering vats, and the resulting product was supposedly sold.
From Chapter 9:
"Worst of any, however, were the fertilizer men, and those who served in the cooking rooms. These people could not be shown to the visitor,--for the odor of a fertilizer man would scare any ordinary visitor at a hundred yards, and as for the other men, who worked in tank rooms full of steam, and in some of which there were open vats near the level of the floor, their peculiar trouble was that they fell into the vats; and when they were fished out, there was never enough of them left to be worth exhibiting,--sometimes they would be overlooked for days, till all but the bones of them had gone out to the world as Durham's Pure Leaf Lard!"
THEY fell into the vats...THEY would be overlooked...All but the bones of THEM had gone out to the world. YOU ARE WRONG!!!
The "where are all the widows" bit is just more of the same strawman.
None of the THEY mentioned above were married? Even if they weren't, they didn't have mothers? Siblings? ANYONE who would miss them?
So, why would Shanek ask questions that had already been answered? I can think of two reasons:
1. He simply forgot. In which case he is dismissing Sinclair as a "woo" without even knowing what Sinclair's claims were.
2. He simply doesn't care. Repeating the same objections over and over will eventually convince someone that there must be something to it.
3. You're a liar and the questions were never answered at all.