OK, look, I hear some of your arguments and I'm starting to change my stand here.
There is a reason why men and women are separated in professional sports: they are completely different physiologically. In general, men have much higher muscle masses and bone masses than women. And men have much lower body fat percentages than women, because men and women have different reproductive purposes.
This is why everytime whenever we see women playing with men in pro sports, they usually fail to make an impact because men and women are completely different.
Ultimately, for Marianne, the team wants her to be motivated, and yes, they should find some other way to do it rather than putting her in men's races. It's all fine and good to say the purpose is to motivate her and for her to learn, but regardless of how she'd do, at the end, she'll have to go back to the sport she dominates, and she'd lose her motivation again. She can't stay in the men's team, and even if she could, and she continues to get bad results, there'd be worse for her career.
Sometimes it's better to be a big fish in a small pond, than being a small fish in the ocean.
This is an overall problem in women's cycling. You don't have enough funding to properly train young talents in these trade teams, so you get huge gaps among the very best and the rest of them. You keep hearing the same names over and over, Arndt, Vos, Pooley, Bronzini, Compton, because how much they dominate cycling and the rest are just hanging on to their coattails. It's a bad way to develop cycling, and would waste a lot of potentially talented riders who could raise the profile of the sport.
Then again, cycling is a very male dominated sport, so there will always be some sexists who think women cyclists are just side dishes. Sites like cyclepassion.com that sexualize women cyclists aren't helping the cause.