Yeah I think it was basically said to be forbidden so that if they did it, they did it secretly. That way none of the others would feel jealous and cause problems.
I have to double check with the translator, but from my understanding:
sex between foreplay men is allowed (as long as they're responsible)
sex between foreplay men and birdies is not allowed
Those were two "studs" having sex, it is forbidden between birdie X stud
oooooooooooh, Thank you !
I didn't really understand the part with the birdie and the foreplay man... So its not forbidden ? just on days off and not exclusive ?