That is quite often the case though. Far too often the victim is blamed, usually over claims of acting or dressing provocatively. If the notion of "boys will be boys" didn't exist in the realm of sexual assaults, then no one would blame the victim, as people would realize it is indeed the assailant that lacks impulse control. But instead society says it's ok to think the victim should not have been dressed in a certain way, should not have been acting a certain way, should not have been drunk, or whatever excuse people will use.
It's hard to determine the proportion of injustice towards accuser & accused.
Whatever the ratio, both should be treated with justice as the goal.
Certainly, we shouldn't presume that all those accused of a crime are guilty.
A separate issue is the confusion of "blame" with "taking responsibility to avoid assault".
If a victim is drunk, I wouldn't blame him/her for being assaulted, but I'd recommend avoiding situations where risk is high.
Even in this forum, people have objected to giving advice that women take care in dangerous circumstances because they shouldn't have to.
Just to clear this up, "boys will be boys" was what the principal of the school said to the rape victim at the school. The whole point of using it in the OP is that it illustrates a terrible attitude.
You had that in quotes, but I also saw different text in the source. Could it be that your quote is a news source's ramping up the language for spin?
I'm skeptical of a paraphrasing of the translation of a 3rd hand account of an extremely outrageous utterance attributed to the principal without corroborating accounts.
After all, Sweden is one of those uber-progressive countries which we're supposed to look up to as a model of enlightened governance.