I'd have to question what you're saying Robbie but not entirely... what you say makes sense but in the context by which most apply the term, I'd have to say that a legal emphasis is likewise extant, if only by association.
"Rule of Thumb" generally (in common inference) refers to a "rule of standard" or "rule of law" -- a common and accepted route of course for those that practice a given craft or discipline.
As a
rule of thumb the idea of legal thrashing may very well have be set within the limits of one's thumb size for the very reason you gave i.e. the thumb as a unit of measure. But you must include the associations or assumptions I've outlined because as part of the social conscience for most of the past 1700+ years the church controlled laws of the land lent permission to men to physically torment slave, female and children not yet of age in just such a manner based on the suggestion made by St. Paul that they were more or less livestock... a possession of men. Which is also why female children were used as currency even into the early part of the 20th century and few ever questioned the practiced because, as a rule of thumb, it was considered acceptable and more importantly, sanctioned by God & Rome.
(Gotta love those convenient Patriarchal rules of governing...)
As To the Issue... yes, I do believe that photos of the gosh-darn plastic things could be censored but I likewise believe it quite ridiculous to censor the words T-H-U-M-B & T-I-P when set together. Believe me, it's not that big a secret... ask most any bartender.
