Sorry to hear your friend was not successfull. I can't answer why he did not make it through to a job but I can assure you that Flightline do not operate any policy that favours one sex over another.
It is true that on occasions certain VIP customers, like football teams for e.g, do ask for female cabin crew. These occasions are few and far between compared to the majority of work. They can be covered easlily by exsisting ratios and in no way would influence the desicsion of employment.
For further proof track down a Flightline Engineer. They all complain there are too many male cabin crew employed!!