As with your pull request the same functionality will be available for both xmlui and jspui I will like to change the configuration option to a single common value (keep the default to false)
# webui.user.assumelogin = true

please move this setting to the start of the JSPUI & XMLUI CONFIGURATIONS
https://github.com/DSpace/DSpace/blob/master/dspace/config/dspace.cfg#L737

and replace the usage of xmlui.user.assumelogin with webui.user.assumelogin in the XMLUI code