> And to me this reads as petulant redefining of terms in the hopes of pulling a gotcha
You are the one doing the petulant redefining.
> But household has always been the combination of a physical house and a social group in it. To claim otherwise is silly.
Not true.
Household has a well established meaning that you are trying to redefine. The referent of "household" is a social group and does not include the house itself. The house is merely part of how that social group can be defined.
If your house is destroyed in a fire, you don't stop being a household while it is rebuilt. If you own a vacation home, the household doesn't change based on who might be visiting the vacation home at any given time.
> Even "family" is typically constrained to immediate family. Such that nobody expects family benefits at a job to extend to their cousins. Heck, we don't even expect it to extend to siblings or parents.
You seem to have trouble with meanings. Just because some employment benefits described with the term "family" are contractually limited, doesn't change the meaning of the word "family". In fact, even the term "immediate family" explicitly includes siblings, spouse's siblings, parents, spouse's parents, grandparents, etcetera.