Lucy regularly beats the crap out of men who are twice her size and much stronger/tougher than she she is.
And this, of course, is completely unrealistic. But, since this is a game, and is entirely fictional, that doesn't matter. Far be it from me to grumble about unrealistic elements in fiction. As long as the story is told well, unrealistic elements are welcome. In fact, I would be inclined to say that the need to embrace the unrealistic is one of the reasons why we enjoy fiction.
All of that being said, I won't try to address the rest of your points, such as Myriam's training, whether or not she would pose a serious threat to a larger man, or whether or not you could put a whole gang to flight by taking out one member. I don't find any of those arguments to be compelling in a real world setting, but I've already stipulated that I'm ready to accept unrealistic elements in fiction, so I can give all of that a pass.
The thing that matters here is that it will be the player's choice. It won't come down to a question of what's realistic or unrealistic in the real world, or whether or not you think it's good character development for Myriam's story arc. If the player doesn't want Myriam to get raped, then, provided that you have been making the right choices all along, she won't be raped. Either she won't get into the dangerous situations in the first place, or she'll escape or be rescued, or she'll kick ass, or some combination of those things. But, if you've made different choices, then she's going to take a length against her will.
It's interesting that Zorlun hasn't included rape as a tag for events we've already seen in the game, even though some would argue otherwise. Including it as a future tag could mean many things, as it may apply to other characters besides Myriam.
But he has included "rape" as a tag - in the game. There are multiple scenes in the game which have a "rape" tag in the game's code.
And, if you've played through all of the scenes in the game, then this won't surprise you, because, even without looking at the code, you will already have seen that there are definitely some scenes which a reasonable person would consider to be rape. But, if you haven't played through those scenes, then you may not be aware of that.
But I will just say that it's just a tag presently, not a political statement on the nomenclature of the word, which just means in the end that there will be some rape thematic in the game, involving Myriam...
I'm glad to hear it.
I don't think that you should shy away from anything which you want to include in the game. Of course, I appreciate things being made optional, because there are some types of content which I would rather not play through. But I'm certainly not going to complain about those things being in the game, when I can just skip over them.