Não é possível atribuir tópico ao grupo

[Lilly (Lillian Louis)]

@JammyDodger

Who can assign this group to something other than ‘nobody’

yes this. as per the Discourse Assign topic:

@Discourse

Also, user groups can be assigned to the topic. In that case, each group member will receive a notification. In group Interaction configuration, you can specify Who can assign this group. By default, is it set to nobody.