He would have organized them.
From Stanley Kurtz’s essential Radical-in-Chief: Barack Obama and the Untold Story of American Socialism, pp. 117-8:
In fact, Obama personally helped plan one of UNO’s most confrontational actions of the eighties [in 1988]: a break-in meant to intimidate a coalition of local business and neighborhood leaders into dropping a landfill expansion deal.
We know of Obama’s involvement in this demonstration only because his supporters in 2008 felt it necessary to rebut charges that, contrary to his claims of inter-racial healing, he had organized exclusively with blacks. Only then did Obama’s former colleagues from UNO [United Neighborhood Organization, a largely Mexican group] of Chicago reveal that he had helped to plan and lead this multi-ethnic demonstration against landfill expansion on Chicago’s South Side.