You really think that is a good solution/good "plan", and would be effective?
Serious question. You really, really do believe/think this?
Whats the point? I never mentioned that this is a good/pefect plan or good solution. But in trouble this will work, you can even enforce it by using a nylon screw, so you will have a single point of brake by specific amount of force, which you easily achieve ( when all the spinach was eaten ;-) )
example screw... (you will have to look for the exact size)
http://www.conrad.de/ce/ProductDetail.html?hk=WW4&insert=V0&WT.mc_id=Froog&productcode=839993&utm_source=google&utm_medium=deeplink&utm_content=dl_article&utm_campaign=g_shopping
Your also can simply lift up the whole visor or open the strap and get off your complete helmet, therefore use a chinstrap splint in a screw shaft in one helmet side. Can be done with ease. it´s up to you... or bonehead ;-)