author here - took that quote from this[1] blog post by an AWS VP/distinguished engineer, the use of "public service" might have some loosely defined meaning in this context.

[1] https://www.allthingsdistributed.com/2025/03/in-s3-simplicit...

Interesting source - looks like it means “GA” service, rather than “public” per se. The SQS beta was also available to the public.