Seems like that might actually make things worse. I think I would rather get thrown from the bike(or scooter in that case) and take my chances than have something placed between my legs. All that momentum would still make your 'boys' hurt a lot.
That wouldn't hold you to the bike... remember, airbags colapse... what it would do is prevent your groin from ramming the fuel tank and handlebars quite so hard.
13% of motorcycle accidents result in groin injuries (Hurt Report).