The trap, though, is that if Clinton activates the machine, she's probably pulling out Obama voters. The risk to Obama isn't so much that Clinton invests -- as her backing from local leaders may oblige her to do -- but that nobody does.
Exactly. If Clinton ponies up, there's really no way to make sure the beneficiaries vote for her. (Reminds me of a Wire episode--season three, I think.) Which means they're unlikely to, since support for Obama in the African American community is so high. If you're a "volunteer" for a local political organization, getting paid by the Clinton campaign is the best of all worlds--you get paid, and you get to vote for the candidate you like. The only scenario you want to avoid is not getting paid at all.
I guess the risk for Obama is that Clinton doesn't have the $500,000 it would cost to activate the local machinery, according to the LAT. (Or that her campaign can make the same strategic calculation Ben and I are making and decides there's no percentage in inner-city turnout.)