as it is, because
侭 centers on a state remaining unchanged: something continuing as it is, or a situation happening because of that unchanged state.
侭 is a phono-semantic compound combining 亻 (person) with 尽, which likely contributes the sound and the idea of exhaustion or completion, but the exact historical development is uncertain.
A person 亻 beside 尽 (exhaust, use up) suggests a state that has been fully used up and remains as it is, without change.
For ジン, imagine a person staying exactly as they are, like a still genie in a bottle: genie -> ジン, and the genie remains unchanged.