It's an excellent ad that was aimed at challenging stereotypes and assumptions (none of those on PPrune, of course) in the wider community, which is probably why it won the Ch4 prize. If you think an organisation is going to provide you with an unsympathetic working environment or, worse, discriminate against you, why would you want to join?
Ethnic minorities are under-represented in the Services for a variety of reasons, one being that the family 'gatekeepers' often don't regard it as a proper career for their offspring. That happened to a university friend of mine, someone of Asian extraction who was offered a pilot slot and an IOT start date shortly after graduation. Whilst his mother was OK with it, his father was not; my friend decided he had to respect his father's wishes, turned down the offer, and has regretted it every day since.
I am reliably informed by a mate in the recruiting system that there are no quotas for females or BAME candidates, but there are recruiting targets, which is an entirely different beast. You do not leave posts unfilled because you haven't got the right number of women, nor do you accept applicants who do not meet the standard. None of the Services has gone down that line. As for basing the close combat argument on Rugby and boxing, I would much rather see it done on capability - if you meet the standard, you are acceptable. Or is that not acceptable?
Battlefields and our enemies do not make allowances for the type, weight, strength and gender of the soldiers they fight against. We cannot put our small soldiers against other enemy small soldiers... It is just a winner takes all fight.
This statement is quite correct until you use it as proof of your argument that women should not be in close combat roles. You might like to use that line with the Gurkhas, who are not known for being especially large? They seem to get by in most wars. History is also littered with the names of women who have excelled in wars where close combat meant a sword or a knife, not a rifle. And there is real truth in the phrase: "Hell hath no fury like a woman scorned..."
That said, if you don't believe diversity is a positive thing, please ignore all of the above.