No Dustin I wouldn't want my DS to do that at all. I am arguing from a Feminist stance (I hoped by putting 'their women' in speech marks to make it clear that was not my phrase but more expressing how the boys would feel under pressure to respond) and I think there are many sad effects of sexism on men and boys and this would be one of them.
I agree there is a huge difference between getting involved in a physical fight to defend your friend from injury or death, which a lot of people, genders regardless, would do - as opposed to being made to feel that, as a man, you are under pressure to "protect a woman's honour" and specifically for boys and men, to do that using physical force. I can imagine a situation where if the boys in the OP had shouted at the German boys, the jeering response would be "So what are you going to do about it?" - and then it quickly becomes physical. We need to equip our sons to deal with situations like that as much as we need to equip our daughters with being sexually harassed for their own safety and others.
This is why all the focus on women avoiding rape is a red herring and a complete waste of public resources. For rapists to be isolated and become as socially abhorred as they should be (as opposed to a page on FB to 'Like!'), the male friends who think "Oh Nigel* is only joking when he's talking about taking a girl up the arse when she's not expecting it - or more importantly consented to it - he wouldn't really do that - it's all bravado/pub chat" have to think to themselves, well so what if he's lying or being the big I am, I'm going to have to say out loud what a pathetic tosspot he sounds and point out that what he's actually boasting about is anal rape in - front of all of our friends. And then speak up fearlessly.
In every stag do trip to a lapdancing club/Amsterdam brothel I'd bet there's at least one (if not more) man thinking, "oh god do I really have to do this to be accepted by my friends, am I going to be called gay** for the rest of the weekend if I don't, it's not even as if it's going to be enjoyable for me and I am going to have to lie to my wife/girlfriend, if I show I'm nervous or uncomfortable am I going to be the one who is bundled up on stage to eat the banana out of the strange woman's vagina because it's just not funny unless someone is being humiliated."
I would like my DS to grow up in a world where he is not obliged to read Nuts or Zoo to prove he is male and whatever talents or skills or interests he has, he can pursue without fear of being told he ought to be interested in sport, or straight men don't really do theatre do they?** All the crap spouted (generally by those who think Feminism is about man-hating and reject it on the basis that they could never be a Feminist because they just don't hate men enough or they're not a sexual prude) about "Boys will be Boys", "All men watch porn" are just plain offensive and while men and boys as a group, and at a societal level, enjoy the advantages of being the gender with the most power, wealth, choices, freedoms etc, at an individual level sexism can be as stifling and life-ruining as for women depending on the impact and the individual concerned.
I don't see shifting the focus from women "keeping themselves safe" to educating men and boys about rape as being idealistic or pointless at all. To think that it's pointless you have to view men as incapable of empathy or compassion or as even incapable of recognising women as flesh, blood and emotion the same as them - let alone political/financial/career etc equals. We are letting our sons down tragically when they can no longer identify whether a quote is from a convicted rapist or their favourite weekly magazine, or even where they are confronted with the fact that the quotes they identify the most with turn out to be those of a convicted rapist, as opposed to their favourite weekly magazine. I would go so far as to say the current level of societal and peer pressure on boys and young men is such that to speak out against rape is a taboo in itself and involves putting yourself in the firing line for ridicule and humiliation. If that doesn't demand some kind of challenge to educate men and boys about avoiding being rapists - which has to start with not admiring rapists or identifying with rapists - I don't know what does tbh.
** Homophobia doesn't just make gay people's lives a misery - stereotypes and expectations also impact on anyone who wants to step outside of their expected gender role
*sorry to any Nigels