Snippets within Tailor

There is a very nice example in demo theme for quick building custom page with repeater (About page example). Is there a way how to use snippet as block there, not only as part of richeditor?

And is there a way how to hide default scope published_at? I tried example:

scopes:
    published_at: false
    published_at_date: false

but it does not affect anything (it’s documented approach).