It is absurd for someone of his background to claim he knew nothing of it before, except as a way to sucker ignorant people into thinking this was something the church covers up. Nor would going around saying ‘Hey, did you know Joseph Smith practiced polygamy?’ be grounds for excommunication. Like I said before, his story doesn’t pass the smell test, not by a mile.
Go and read 1 Cor 5, Paul tells the saints there to excommunicate a member for marrying his step-mother (’Therefore put away from among yourselves that wicked person. v13). Paul made it clear that he didn’t want that person’s presence to be a corrupting influence on other members. Are you going to call that cultic too?
It isn’t about being ‘fearful of investigation’ it is about upholding standards. If your church (care to actually say which one it is?) has no standards that members must adhere to that is it’s own business. I can certainly see why Satan would have no need to send a wolf in sheep’s clothing into a congregation of wolves though.
Also, excommunication is a merciful act. When a person is baptized they make a covenant with God. If later on they have no intention of keeping their part of it, it is better for them to be released from that obligation than to continue violating the covenant they made. If they then repent, they can be baptized once again, starting over fresh.
Only in Mormonism, is questioning history akin to marrying your step-mother.