Hi Harold,
I'm not familiar with the context of your conversation with TAC Team so can't comment on that.
However, in general active is configured only on one of the peer so that traffic gets forwarded via one peer and split brain scenario doesn't arise when the ICCP peer goes down.
https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/mc-ae-edit-interfaces.html
prefer-status-control-active—Specify that the node configured as status-control active become the active node if the peer of this node goes down. When ICCP goes down, you can use this keyword to make a mc-lag PE to become the active PE. For example, if you want mc-lag PE1 to be Active on ICCP down, then configure this keyword in PE1. It is not recommended to configure this keyword in both the mc-lag PEs.
PS: Please accept my response as solution if it answers your query, kuods are appriectaed too!
Thanks
Vishal