It's a very easy question, almost all countries have resolved answers for it. They don't all agree, but it was very easy to answer. Many of them have clear, objective standards on how to apply the rules (that people choose to ignore or argue over), though some certainly are determined to make it as fuzzy as possible for their own agendas. You can easily find local regulations addressing this topic pretty easily for most parts of the US and european countries, also some other countries like Japan.

There's also the standard fallback answer for "which bathroom": if you make them all single occupancy, it doesn't matter which one. Sometimes that's the solution used in situations like schools.

So maybe pick a better example of a hard question that seems easy. (Though I get the relevance here, given the decried panelist's history and views)