I find many unfamiliar phrases in readers' comments on the statements of political figures and articles on news sites these days. I can't tell if they are accepted usage. Comment posters could be native English speakers or non-native speakers. I cannot judge, and it is frustrating.
In The Washington Post’s “Comment of Today” (May 13), I came across the phrase, he is a proven commodity. The comment was in response to Chris Cillizza's "The most eventful week of the 2012 Republican primary race":
Put the pieces together and Ron Paul has a very good chance of winning the Republican nomination. The GOP is suffering from an enthusiasm gap with the rest of their 2012 possibilities. No one excites the base like Ron Paul. And he is a proven commodity in terms of raising funds and knowing the ropes of running for president.
I understand “a proven commodity” is a metaphor, but can a person be called a commodity? Is the expression, he is a proven commodity normal American English that I can use to describe any of my friends in conversation with my peers over a drink?