Arnie, the caring pop, has no idea where his daughter is in the president's complex, so he thinks, "Ah! I shall blow up every single building even though my daughter may be in any one of them." Also, watch for the really badly made model soldiers that don't move even when the buildings explode. Nice one!
Being that arnold supposedly has prior military experience based on what i've seen at the start of the movie,he would know which buildings would house the quarters for the soldiers so he figured he'd blow them up to increase his advantage,he figured his daughter was being held in the nicest looking house of the property think about it!
Of course not! Can´t you remember that he can sniff people? He smelled his daugther, and he just knew right away where she were hidden. After all, she was 24 hours without a bath. Maybe that´s part of F. Kirby´s training, a bio-improvement to add olfactory receptors to the perfect soldier.