No offense taken. Preferences are preferences and there is no "wrong" answer to somebody learning to ride. Motorcycles offer freedom.
(part of me had wanted to say, "Stop being such a girl!")
Here's my point (again):
As with firearm users... don't buy a dinky .22 pistol to learn how to use a firearm if you're going to be carrying a concealed weapon for self defense or becoming a law enforcement officer. You'll get little out of it. Learn on what you'll use. Go out and buy the Glock or Sig and train on it. You'll suck at first, but the learning curve is much sharper and you didn't waste money on that initial step.
Safety measures are the same regardless of the size of the bike... whether it's a Huffy, a Vespa, a Honda Shadow, or a Valkyrie Rune. Point: Don't do dumb shit. Safety measures remain the same: proper maintenance, proper safety equipment, proper attitude, and proper riding location.
Motorcycle Safety Statistics:
http://www.webbikeworld.com/Motorcycle-Safety/crash.htm
A motorcycle (even preowned) represents a significant investment of money for a young person. Buy something you won't grow out of quickly to save the heartache and walletache of upgrading in a year.
You wouldn't recommend somebody learn how to drive a car by using a riding lawn mower... so why would you essentially do the same thing with a motorcycle?
In my opinion, a bike with less than 500ccs is a toy and is not something I'd trust anybody with on a highway. No balls. A underpowered motorcycle is like a dull knife... it's lack of decisive performance gets people injured. Acceleration is a useful tool on something that has half the wheels of a cager (person who drives a car) and requires the operator's feet to stay upright at a stop.
...
I'd never ridden a motorcycle before March '07 and the first bike I purchased was a 1100cc Honda Shadow Sabre. I was extremely careful with it, took the rider safety class, stalled it around the neighborhood a zillion times, and now I take it on weekend trips from Maryland to Virginia to Pennsylvania to West Virginia.