Why a nuclear chokepoint weapon signals a failed strategy

Would an enhanced-radiation Tomahawk be useful for closing a maritime chokepoint?

No. Conventional ways to disrupt a chokepoint are easier, so needing the nuclear weapon would indicate a deeper strategic failure.

A nuclear Tomahawk optimized to irradiate a maritime chokepoint would be an unnecessary escalation. Conventional means could disrupt or deny the same route more easily. Reaching for the nuclear option would therefore reveal that simpler strategic and operational measures had already failed or been neglected.