Doesn't stop removal of image

Does as expected, preventing posts from being published without the image.
However, it doesn’t stop someone from removing the featured image and updating an already published post.

Replacing:
if ($new_status === ‘publish’ && $old_status !== ‘publish’ && !rfi_should_let_post_publish( $post ) )

with:

if ($new_status !== ‘draft’ && $new_status !== ‘trash’ && $new_status !== ‘auto-draft’ && !rfi_should_let_post_publish( $post ) )

Seems to fix the issue.