The July 1980 edition of Omni, in which the Herbert's article appeared, is available on archive.org in various formats [1]. The full collection is at [2] and was discussed a few years ago on HN [3].

[1] https://archive.org/details/omni-magazine-1980-07

[2] https://archive.org/details/omni-magazine

[3] https://news.ycombinator.com/item?id=4741619