The ethical side is up to you, but in a strictly technical sense I don't think there's much that Google could do to intrude on your users privacy as a result of them issuing your SSL certificate, even if they wanted to. AIUI the ACME protocol never lets the CA see the private key, only the public key, which is public by definition anyway.

A more realistic concern with using Googles public CA is they may eventually get bored and shut it down, as they tend to do. It would be prudent to have a backup CA lined up.