Hi there,
To hide such post, you can configure them based on your blog post category permissions as you can see here
https://screencast.com/t/OUfuzCtj and it is based on Joomla users groups as you can see here
https://screencast.com/t/eVf7Kj2Icn.
But from my view, by using team blogs is much better, where you can control them without dividing and creating a new user group for your users.
Maybe i can help you explain a bit regarding team blog workflow.
1. Create team blog on your site based on 3 access as you can see here
https://screencast.com/t/bT3kPtcwR as explained below.
Team members only - All blogs created here can be accessible by users that have joined your team only
All registered users - It will be accessible by users that are registered on your site only and meaning that guest users cannot see them
Everyone - Any users that access your site can access your site, including guest users
2. You can choose configure whether your users can join those team or not as you can see here
https://screencast.com/t/OcEnOJNK0J5S
3. Create those blogs accordingly and assign it to that team as you can see here
https://screencast.com/t/yu5SJXeX7Abu