Do s3 buckets have to be public?

I’m working on creating an internal blog (no public access). I’d love to be able to use this plugin to upload media to an s3 bucket, but the bucket and its objects will also not be publically readable. I noticed this line of code and am worried that s3 buckets without public read perms won’t pass the perms checks:
https://github.com/deliciousbrains/wp-amazon-s3-and-cloudfront/blob/master/classes/amazon-s3-and-cloudfront.php#L2634