Despite the criticism of his choices, he seemed completely unbothered.

unbothered 是由前缀 un-（表示“不”）和动词 bother（打扰、烦扰）的过去分词 bothered 组合而成的形容词，字面意思是“没有被烦扰的”，引申为“不在意的、无所谓的”。