Jack Vance's "Rumfuddle" (novella, mystery): To improve human history, put would-be evildoer babies elsewhere

Couple of caveats first, particularly for readers from the East:

1. This is the first story of Vance where I found a para obnoxious for racist reasons - Orientals are dirt, filthy; the idiots need to have the superior western world view forced; etc. A character says it, & I understand that may or may not reflect author's views. Still...
2. Significant parts of the story refer to figures from European history, & parts of Asian history presumably well known in the West. Mostly, but not always, to villains from history. A lot of them were unfamiliar to me; story may mean more to those better familiar with these figures.
3. There is a sentence in the story that could cause riots in some Muslim countries. I won't quote it.

Key science fictional device in the story is a portal that can instantly convey you to:

1. another world somewhere in galaxy or outside it, similar to Clifford D Simak's "The Big Front Yard".
2. to a time & place in earth's past.
3. Either of the above in a parallel universe. Actually, if I understand correctly, travel to past is always to a parallel earth rather than ours.

"Rumfuddle" is a kind of party; "Rumfuddlers" are party-goers. The origins of Rumfuddlers are pious: do-gooders who travel to the past to remove history's evil doers like Hitler, when they're still babies, to other environments, where they won't grow up to do evil. With time, the execution of the idea degenerates, & has to be eventually stopped.

Story summary.

Gilbert Duray works on earth but lives at Home, a whole world to himself, as many others do in this universe of infinite available worlds. His children go to school on earth too! Transport is easy - you step through the "passway", as you would cross a door.

One fine day, Gilbert finds the portal back home "closed" when returning from work. Checks elsewhere show all portals to his Home are closed. It means his wife & three daughters are now marooned, forever cut off from him & rest of humanity.

Story is of his work on unraveling the mystery. Happy ending, eventually.

Notes.

1. Story uses the word "cognate" to designate "corresponding" in a parallel universe. A parallel earth is a cognate earth. Gilbert from our earth meets his wife Elizabeth's cognate in a parallel earth. Etc.
2. Evil-doers are removed as babies, presumably from a parallel earth, to our universe, at least in some cases. Means our own history is unaltered? Only some parallel universes get a better history? Going to so much trouble changing history for betterment in a parallel world! Sounds too idealistic to me.
3. How come time never comes in the way traveling instantly across worlds? I mean, kids go to school & papa goes to office in the morning - where morning at Home & in office world or school world is always the same?

Collected in.

1. David G Hartwell (ed)'s "The Science Fiction Century".

Fact sheet.

First published: Robert Silverberg (ed)'s "Three Trips in Time and Space" (1973).
Rating: B.
Related: Stories of Jack Vance.