In legal defense cases, they always fall back on the excuse that shunning is a decision that individuals make of their own volition, nobody forces them to shun.
Also, there is the concept of 'ratification', which in essence means that a person who, upon reaching the age of majority, abides by the terms of a 'contract' that they entered as a minor, the terms of the contract are upheld. This too has been used to weasel out of legal wrangling related to the baptism of minor children.