I've credited it to Leonard Nimoy, yeah. I went and listened to it, and it does have some orchestral backing and sound effects sampled from elsewhere on the album, but Nimoy is the only one explicitly credited for the track so I left it.
Which raises another question: how do you create a relationship for someone who's credited with "sound effects design, recording, and production" (digital, not vocal). (Well, I went with "recorded by" and "producer", but still not sure about "design". Does that count as composition?)