Yes - this was in part to cover the case where distributor is only active on one gateway in a redundant pair.
Your assumption on running redundancy is correct. MQTT Engine will only attempt to connect to an MQTT Server if it is the ‘active’ node in the redundant pair.
There is no harm in having Engine connect to two MQTT Servers simultaneously as long as there is no duplication of Sparkplug messages that are arriving. This setup is also still possible. You’d just need to have two server sets with one MQTT Server definition in each set.