How to manage Consul and its quorum in auto-scaling environments?
I would set the leave_on_terminate option to true. As per the documentation


  leave_on_terminate If enabled, when the agent receives a TERM signal,
  it will send a Leave message to the rest of the cluster and gracefully
  leave. The default behavior for this feature varies based on whether
  or not the agent is running as a client or a server (prior to Consul
  0.7 the default value was unconditionally set to false). On agents in client-mode, this defaults to true and for agents in server-mode, this
  defaults to false.


What happens when a node is shutdown gracefully is to send SIGTERM to all processes before shutdown, with this setting on the consul agent will leave the cluster so it won't be considered as a node which can restart and be back in the cluster in a few hours (which is what your quote says it does by default).