Oliver was in need of some information. He didn't have the valuable resources here, that he had back in Metropolis and Star City. It was one of the reasons why he had sought out the public library. He was looking for the archive section. He wanted to know more about this city's history and whatever information he could gain on a few of its residents.
Never once did Oliver forget that he was out to help Chloe. Not for a minute. But, if he was going to find her, and he would - no doubt about it, he needed more information. He decided to hit the computers first, see what he could dig up there. It never hurt to look.