 Raymond comments, " ' Ninian was a ninny to locate in a mercantile suburb where any little thing out of the will cause talk.  How thankful I am that our era has completely disposed of the mercantiles --' "

What irony can be found in this statement?
Nobody in the neighborhood was surprised when Martin's mother disappeared and Ninian came to take care of him. "He's dissatisfied with the current social order and killing you is part of an elaborate plan he's formulated to change it. There were hot water and heat all the time and a freezer well stocked with food—somewhat erratically chosen, for Ninian didn't know much about meals. It was then that Martin began to realize that either the whole lot of them were insane, or what Ninian had told him at first was the truth. You see, he's an idealist," Raymond explained, pronouncing the last word with distaste. And, on those worlds, it's far cheaper to use native labor than to ship out all that expensive machinery.
 Rather than be grateful that gossip has been eradicated in the future, Raymond is thankful that an entire class of people has been eliminated.
 It truly is sad that someone who had the insight to create a plan as detailed could not have avoided living in such an area.  He calls the master behind their grand plan "a ninny."  Raymond has no right to call anyone "a ninny," as he is the dumbest descendant to arrive from the future.  Rather than be grateful that gossip has been eradicated in the future, Raymond is thankful that an entire class of people has been eliminated.