Mohammed Aly does not see any reason why he shouldn't try to ease the lives of Orange County's homeless. But the authorities — and many of his neighbors — disagree. Aly, a 28-year-old lawyer and activist, has been arrested three times as he campaigned on behalf of street people. Recently, he was denied permission to install portable toilets on a dried-up riverbed, site of an encampment of roughly 400 homeless. "Put yourself in their position: Would you want a toilet, or would you not want a toilet?" he asked. "It is a question of basic empathy."...