Balsas, whose lawyer said was a professor of urban planning at Arizona State University from 2004 to 2011, remains in prison with bail set at $250,000.
Edwin Haury, a security screener at the pavilion, testified that about 10 a.m. Jan. 26, Balsas entered the pavilion carrying a courier sack and backpack.
Haury said Balsas asked him, "What do you need?" and he replied that he needed to search the bags.
Haury said Balsas refused to let him look in the backpack and said, "I have explosives in there."
When an armed security guard joined Haury and repeated the request, Haury said Balsas grabbed the bags, said, "This is the way they treat you in America," and walked out.
Balsas was followed by National Park Service rangers west on Chestnut Street and north on Seventh Street before being arrested at Market Street.
Ranger Layla Schade, who was among the group that arrested Balsas, testified that when Balsas was stopped he refused to remove his hands from his pockets.
Schade described Balsas as having a troubled look on his face and said he stared into the distance while rangers tried to question him.
Defense attorney Mythri Jayaraman said Balsas - a citizen of Portugal who has lived in the United States for years and who obtained a doctoral degree in Massachusetts - had undergone a psychiatric evaluation and was found competent for trial.
Balsas did not speak during the preliminary hearing. He mostly stared straight ahead through wire-frame glasses, his jaw clenched.
Jayaraman declined to comment about what motivated Balsas.
Although the threat did not force evacuation of the pavilion, Assistant District Attorney W. Robert Frantz Jr. said Market Street was blocked while bomb squad officers inspected the bags. No explosives were found inside.
"If it was a joke, it was a poor joke that didn't leave anybody laughing," Frantz said.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.