There's logic behind that. Most people who are buying morphs are buying to breed. And the higher-end the morph, the higher the price. So it makes sense to get a normal or het female and the cheaper male for the morphs to breed to her. Plus, on a simpler note, females make babies, babies make money, therefore females are more valuable.
Also, handling a boa of any size is doable, as long as you're smart about it. I'm 4'11" and getting a boa in about a month, and once it breaks 6 ft, I won't handle it alone. That being said, I believe Tarahumara Mountain boas are the smallest of the dwarves, but I'm not sure.