I would totally agree with the basic premise that guys are, on average, worse off due to the testosterone, but would still suggest that you can learn better riding skills, faster, on a smaller bike. That's true for men or women. The lack of aggressiveness, assuming it exists, might help with basic survival from accidents caused by pure stupidity but it won't help with the learning curve to become a really good rider. That's acquired skill. Those skills defy most basic human instincts and reactions and are more easily learned on something a little less powerful. That's the part that too many non-riders, or inexperienced riders who only think they know what they're doing, male or female, don't grasp.
It's understandable that they don't understand as there is no built in point of reference in the normal human experience or inate human skills. That is very evident when reading the posts and arguements that go back and forth between experienced riders who have truly become quite skilled, and novices.
At the level of riding that starts at track days and up to the fastest racers, I am yet to hear anybody suggest that what they do with a bike has anything to do with "balls", but is all acquired skills. When they are doing what they do so well, it may be intense due to extreme focus, but is never just a guess nor is it truly terrifying scary. It is all consciously timed and executed moves to do exactly what they feel the bike will do and quick, often subtle, reactions to feedback from the bike as it moves along. If it were anything else, they'd crash, and when they get overwhelmed they do crash too, just like the mere mortals. Those are acquired skills, not natural. They are best acquired on a forgiving machine.
I'm not trying to suggest that all riders need to be racers. After all, even the fastest racers didn't do that the first time they sat on a bike. The point is, the more skills you've got, the safer you are. You'll acquire those skills faster on a more forgiving bike. A couple of years and 10,000 miles or so experience on a smaller bike will set you up to better handle a 600. It will not have you mastering the situation but hopefully enough to keep you safer as you continue building your skillset.
Many of the accidents on bikes that are not caused by sheer stupidity or lack of defensive driving skills, are caused by lack of braking skills, lack of cornering skills, lack of proper throttle control, and the always present "gravel.... nothing I could do". Being a rider for 35 years or so at about 20,000 miles a year, riding the same roads everyone else is riding on, last time to dump a bike being around 1976, I'll tell you there IS something you can do, and that's work on your skills on a bike that's forgiving. (If you do the arithmetic, you'll notice that 2004 - 1976 does not = 35)
As the skill level goes up, the ability to deal properly with the additional power also goes up. If you're dealing with the additional power as you're trying to acquire the other skills, your learning curve is dramatically hindered by the addition of that one more BIG disadvantage, a hard to control throttle. Again, even the racers crash sometimes, when they've gone beyond their abilities.
I know this can be hard to grasp for many. I didn't understand when I started either. You'll have to take it on blind faith and trust that it's the proper advice most often given by truly experienced riders. Good luck.