I agree with you, not your cousin because that situation implies there is a good degree of visibility which safeguards everyone (as most men are good men and would stop an attack if they knew it was happening).
I think all men are safer in men’s toilets that are designed properly because the alternative are different designs.
When you look at actual recent U.K. evidence, which I believe I am the only person to have done in terms of design, it is the design of the toilet compartment that is important. Boys and girls and women seem to be targeted. I think there’s a case that unisex private toilets are more dangerous. It is the privacy which determines misuse.
All mixed sex toilets are private. It is regulated that way. All ‘gender neutral’ (unregulated) designs mention privacy. Your cousin is technically arguing for all toilets being a universal/unisex design.
In design terms, if you have men going into women’s toilets (with the common sense exception of cleaners) then the designs have to change to stay within regulations and legislation to be unisex. They get rid of the door gaps that prevent misuse and get made bigger to hold a sink and dryer and are made into more sound resistant rooms. It doesn’t take a genius to work out that is less safe.
We have enough evidence from what’s going on in schools, from past British Standards, and what has happened in ‘disabled’ toilets (the reason RADAR keys were introduced), the all the reasons for most council run toilets closing, to show that sex in toilets is always a problem.
Single sex toilets can have door gaps only in a single sex environment. They are there to safeguard, for ventilation and for cleaning.
There have been situations eg. where a desperate man has attacked a young boy in a male toilet cubicle and it has been stopped by people seeing and hearing what’s going on by the floor-door gap. But I think the gaps also prevent situations happening in the first place. It’s a risky thing to do as the chances of getting caught are high.
But, to be fair to your cousin, men’s toilets and sex is a problem. There’s websites where you can arrange hook-ups. Men used toilets when homosexuality was illegal but it continues as a destination today. These can be in shopping centres or supermarkets as well as parks. So there’s possibly a chance your cousin has seen/ heard sex in toilets and therefore has a different view on what goes on in toilets.
All sexual activity in toilets has been illegal since 2003, although it was argued against by a male MP that it was discriminatory against men to make it so. There’s certainly not much appetite to prosecute like there was in the 80s and 90s. It’s not a popular opinion but make toilet cubicles less private and ensure men know it’s illegal. People don’t like getting caught or named and shamed. That safeguards all people wanting to use the toilets for sanitary purposes.
We have lost so much provision since the 80s and 90s due to men’s behaviour. The ‘answer’ has been that toilets just get shut down.