Although "rule of thumb" was, according to the OED, in use before that 1782 decision, the furor that arose from that decision may have _redefined_ the phrase in the common vernacular. Whether it was originally meant as sarcasm, as an attack on "Judge Thumb," is probably difficult to determine. Given that public sentiment was against Judge Thumb's ruling, it seems to me that it was originally intended as sarcasm, and any ultra-feminists who take "rule of thumb" to be misogyny are doing it to advance their cause rather than to set the record straight.
collected links:
http://www.straightdope.com/columns/000512.html
http://www.canlaw.com/rights/thumbrul.htm
http://lawlibrary.ucdavis.edu/LAWLIB/oct95/0125.html
http://www.wordorigins.org/wordorr.htm
collected links:
http://www.straightdope.com/columns/000512.html
http://www.canlaw.com/rights/thumbrul.htm
http://lawlibrary.ucdavis.edu/LAWLIB/oct95/0125.html
http://www.wordorigins.org/wordorr.htm