No not really - for the following reasons:
* the 2 Blacklists serve quite different purposes - see
https://pmg.proxmox.com/pmg-docs/pmg-admin-guide.html#pmgconfig_whitelist_overview
(one is for users to define that they just want mails not to get put in quarantine but rather blocked directly or delivered directly, the other is for the admin to define which mails should be rejected)
* the global blacklist who-object is just there in the default config - there is no guarantee that it is there
I would say that an admin should review the mails they put on their global blacklist - and they can already view the black and whitelists of all their users
I hope this explains it