BANGKOK—Thailand’s military junta might have got the result it wanted when former leader Yingluck Shinawatra fled the country before a court could hand down a verdict in her negligence trial last week.

Her flight freed the generals from the risk that she could be viewed as a martyr if she were convicted and jailed for allegedly mismanaging a botched multibillion-dollar rice subsidy. Ms. Yingluck, 50 years old and the mother of a young son, was facing up to 10 years in prison for a crime she says she didn’t commit. Thousands...