Timing, Pressure, Fear.

I won't go so far as to call you cowardly. If it had been a one on one conversation with someone like your cousin, and you said something you did not believe in, then maybe.

You made the pressure and tension in the room very clear in your narrative. If anyone is going to call you a coward for your response (under pressure) in this situation, they have to call themselves cowards for not being more public with THEIR opinions (Note - I don't KNOW what level of public discourse they have had, but I doubt there is a lot). It is easy to post things in a forum like this, but not so easy when you might out yourself.

With 20/20 hindsight, it is easy to say, "I would have stood up for our rights" or "I would have responded thusly...". In reality, you were on the spot and one of the thoughts zooming through your head in that fleeting and nearly unconscious instant of decision was probably, "Will I get myself outed if I respond in a way they don't expect?"

As you also pointed out in another response, the question was posed as "sexual assault" not "having sex." If I walked in on someone assaulting (sexual assault or regular assault) a child, I would take whatever action was necessary to stop the assault. If it was a severe assault, I would probably take more action than would be legal out of fury. BUT... if I walked in on them having sex (no screams or crying), I would like to think I would take a moment or two to analyze the situation.

Would I turn in someone for having consensual sex with a child? Depends on the situation, but probably not. The only issue with NOT doing so is that I would expose myself to liability for having done nothing if the "perpetrator" is later caught. The child might say in an interview, "but LGL40 knew!"

I was in a real life situation where I saw some CP on someone's computer. Others were about to enter the room and there were those present who would have acted on it (called the police, etc). I was able to tell the guy quickly to turn off his computer, which he did. Was what I did legal? No. Do I think what he was doing was worth him going to jail for years and years or even decades? To me, that is more immoral than not turning him in.

I feel the same way about consensual sex with minors.