Arnold can suggest anything in a book but that does not mean he used an arm blaster, or saw any value in it, for himself in the old days. Or any other piece of special equipment for that matter. Some people will believe anything they read when written by their hero's they worship. Seems the obsession with the front delts when curling and now doing triceps overwhelm some people. Time to think out side the established box to understand training better. Or perhaps a course in Bodybuilding 101 may help for the past coach of the Bahama BB'ing team? Good luck.
Bizarre self-ownage by our easy-reader considering that standing strict curls are entirely in the box established thinking LOL I'm clearly suggesting that one open thy mind and try alternatives.
What's irrefutable is that Arnold continues to support the thing now when he gains nothing financially. I know from your reply that you didn't know that and can't effectively rebut.
Coleman didn't espouse strict weight curls, neither did others like Scott. Scott in fact believed and practiced (1) isolation exercises on preachers and pedestals, and (2) the use of loose not strict form, within that context.
A lot of the top guys past and present do not do strict BB curls. They're good but many have found that variations on the theme are better. Open your mind and try many things. 
