If you include contamination from the Chernobyl reactor disaster as “having a (piece of) reactor" then they were also correct.
Not a single one had one either :p
I think the joke is that there were no Soviet housewives in the year 2000 anymore, so the statement "all Soviet housewives now have a nuclear reactor in their home" is correct.
As is the statement "all Soviet housewives do not have a nuclear reactor in their home", which I think is what your parent poster said.