Irony, or ignorance?

The title Southern Slavery As it Was seemed awfully familiar. Finally I remembered: American Slavery At it Is: Testimony of a Thousand Witnesses (1839), by William Weld, served as a powerful witness for the cause of abolitionism.

READER, you are empannelled as a juror to try a plain case and bring in an honest verdict. The question at issue is not one of law, but of fact--“What is the actual condition of the slaves in the United States?” A plainer case never went to a jury. Look at it. TWENTY-SEVEN HUNDRED THOUSAND PERSONS in this country, men, women, and children, are in SLAVERY. Is slavery, as a condition for human beings, good, bad, or indifferent? We submit the question without argument. You have common sense, and conscience, and a human heart;--pronounce upon it. You have a wife, or a husband, a child, a father, a mother, a brother or a sister--make the case your own, make it theirs, and bring in your verdict. The case of Human Rights against Slavery has been adjudicated in the court of conscience times innumerable. The same verdict has always been rendered--“Guilty;” the same sentence has always been pronounced, “Let it be accursed;” and human nature, with her million echoes, has rung it round the world in every language under heaven, “Let it be accursed. Let it be accursed.” . . .

The gap between "as it is" and "as it was" is enormous. Did Wilkins and Wilson know what they were alluding to, or was it lost on them?