When using ezpublish:legacy:script command, CLIHandler is used as legacy kernel handler, wrapping eZScript.
This service is built by ezpublish_legacy.kernel.lazy_loader factory service. The factory injects a hash of parameters, as expected by eZScript.
Problem is that this hash of parameters, referenced by ezpublish_legacy.kernel_handler.cli.options, is empty. This makes eZScript use default values, which is most of the time OK.
However, use-modules option is set to false by default, which makes impossible to use operations (e.g. content/publish) from legacy scripts.