I don't agree with you that personal safety risk is not a justification for excluding all male people from a toilet designated for female people to use.
You don't seem to be able to articulate clearly what you are trying to point out. I am still not quite sure what your point actually is.
Are some spaces needed by people better with higher traffic flow, even if that is mixed sex traffic? Maybe there is an argument for this, but no where will have the constant traffic needed at all times, so how then is this relevant for a discussion on single sex spaces?
Just because there is little traffic into the space, doesn't mean that the traffic into the space is not being monitored formally or informally.
Also, you then tried to reduce safety to male people leaving spikes on seats as if that is relevant. Male people do not have to be doing anything other than being in that space that they should not be in to be causing harm and making them unsafe.
Just them deliberately entering into a space that they know and fully understand is for female people only is them doing so knowing that their presence can cause distress. And doing so deliberately should be called what it is, an act of intimidation at the worst, or complete disrespect for female people at its 'least risk'.
A male person who is in there knowing they shouldn't be there is exhibiting 'risky' behaviour.