 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?
No one, least of all Martin, could dispute that a man's life should be guarded by his kin—but by those who hadn't been born yet? 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. Though they were in the house with him, in their minds and in their talk they were living in another world—a world of warmth and peace and plenty where nobody worked, except in the government service or the essential professions. There was no devastation, no war, no unhappiness, none of the concomitants of normal living. 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. When Martin was sixteen, Raymond took him aside for the talk Ninian had promised five years before. You see, he's an idealist," Raymond explained, pronouncing the last word with distaste. "And Conrad really got upset over the way Earth has been exploiting the not so intelligent life-forms on the other planets," Raymond continued. We're virtually the same people ... although it is amazing what a difference two hundred odd years of progress and polish can make in a species, isn't it?" And, on those worlds, it's far cheaper to use native labor than to ship out all that expensive machinery. "I'm trying to talk to you as if you were an adult," Raymond said, "but if you will persist in these childish interruptions—" "I'm sorry," Martin said. But he wasn't, for by now he had little respect left for any of his descendants. In that way, there would be no space-drive, and, hence, the Terrestrials would never get to the other planets and oppress the local aborigines. "It's the adolescent way," he said, "to do away with it, rather than find a solution. "I wormed the whole thing out of him and all of us—the other cousins and me—held a council of war, as it were, and we decided it was our moral duty to go back in time ourselves and protect you."
 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.