But, that doesn't mean the account holder can make up his own definition of "household" either. Just because someone wants to justify their stream sharing doesn't make "my ex-gf's junior year dorm mate" a member of the household. If this ever made it to court, the court would likely look at the common and reasonable interpretation.
And, let's face it, all this whining about whether Netflix is trying to charge people when they travel is just BS. Any reasonable person knows what Netflix is trying to cut down. People that share their other people, often with little or no relation to the account holder.