No, if you want to prevent any obstacles from blocking damage, you don’t need to change any collision settings of actual shapes. You just need to create a new query-channel under project-settings->collision, set the default response to ignore and use that channel as parameter in the ApplyRadialDamage node. This way you have a query-channel that will never actually hit something…
About the impulse: In that case, the example probably uses the component, not the “loose” function.