He thought they were criminals, and they had confessed to the crime at the time. Asking for the return of the death penalty to deter heinous crimes isn't that bizarre. Plus by the sounds of it they, or at least members of the group they were with, were up to no good in Central Park that same night.

a group of more than 30 youths had entered the park from East Harlem. Some engaged in a rampage of random criminality, hurling rocks at cars, assaulting and mugging passersby. Among the group was Salaam, along with 14-year-olds Raymond Santana and Kevin Richardson, 15-year-old Antron McCray and 16-year-old Korey Wise. The teenagers – four African American and one Hispanic – would become known collectively as the Central Park Five.

So a confession mixed with other notable crimes being committed was probably enough to convince most people. Hence their conviction. Was it wrong? Yes. Was he wrong? Yes. But it had nothing to do with their race. It was about rampant levels of criminality.