Project based snippets should follow project access permissions
When Snippets are used inside of a project, only the original author of a Snippet can make changes to the Snippet. This is confusing to members of the project as they might have permissions to edit other types of content, but no permissions for this.
Snippets created inside of a project should use the project permissions to determine who can edit/modify the Snippet.
What isn't in scope?
Snippets created in a user's personal namespace should not have additional permission options, nor would a complicated permissions model make sense here.