To suggest that supplementing with Magnesium Chloride is a "scam" is irresponsible. Magnesium is required for life. Additionally, Magnesium is known to be poorly absorbed when taken as an oral supplement due to it's alkaline property.
That being said, if you are challenging the ability for Magnesium Chloride Oil to penetrate the dermis for systemic benefit, perhaps you need research how transdermal applications work.
If you are very certain that compounds cannot pass the protective skin / dermis for systemic benefit, I suggest you pick up some Androgel (or any pharmaceutical testosterone gel) and apply it to a few women and a couple kids just to demonstrate your confidence. Do that for 30-days and report back.
NOTE: I'M NOT REALLY ADVISING THIS, HOWEVER MAKING A POINT. IF YOU TRY THIS AT YOUR OWN RISK, DON'T BLAME ME SINCE ACTUALLY BELIEVE IN THE Science BEHIND TRANSDERMAL ABSORPTION!