lock-my-bp - Good for locking any CPT

https://wordpress.org/plugins/lock-my-bp/

Create private BuddyPress community by locking certain BuddyPress Components, WordPress Pages, Custom Post Types for public view without using any membership plugin.

Also, worth looking at - allows for moderation/lock even after user registers and activates their account.

https://wordpress.org/plugins/bp-registration-options/