Earlier quoted context omitted.
No, copyleft doesn't prevent commercial use. In fact, preventing commercial use is impossible with the GPL.
Sorry I was under the impression copyleft meant that commercial users must purchase a license and normal users could use it for free. Is this what CockroachBD just did?
>The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.
From the FSF's "What is free software?" page[1]:
>A free program must be available for commercial use, commercial development, and commercial distribution.
Licenses like CockroachDB's with restrictions on commercial use are "source available", which is a form of proprietary software.