But once again, his argument is that 6 of 11 states didn't mention slavery. So by his argument, "that does not mean that they did not consider the issue of slavery high on their list of priorities."
Or obversely, the fact that 5 out of 11 mentioned it suggests it was very high on the list of priorities. Or the fact that 5 and 2 suggests that slavery was a lot more important than tarifs.