[updater] uninstall { critical = true } packages?

Uninstall("firewall", "kmod-ipt-core", "kmod-nf-ipt", {priority=100}, {critical=false})
Uninstall("firewall", "kmod-ipt-core", "kmod-nf-ipt", {priority=100})

does not work but producing

Request not satisfied to uninstall package:

How to get rid of those then?

Package("firewall", { virtual = true })

works