Yeah, the RSS on Mastodon only shows posts that are public anyway.
If you use non-public posts on Mastodon, they will not appear in the RSS feed.
So, the RSS feed doesn't really affect privacy on Masto.
And yes the .atom feed seems to have gone.
By the way, I've got RSS instructions on the fedi.tips website too:
https://fedi.tips/how-to-use-mastodon-and-the-fediverse-advanced-tips/#FollowingAccountsThroughRSS