MWG for HA will distribute traffic between the various scanning nodes, when it does this, its at Layer 3 (tcp level).
However if you are distributing traffic over WAN links or long distances I would have concerns that traffic might be interrupted.
This thread discusses how you can prevent a node from distributing traffic by creating two separate clusters.
In the thread above, the goal was to create separate virtual IPs AND disable traffic distribution.
Disabling traffic distribution alone might be the goal here, however a physical load balancer might have better health check capabilities in order to determine if there is something wrong in the path.
Thanks for your answer.