In general, private organizations have been pretty free to use social pressure (such as withholding of social reciprocity, denial of social support) to punish dissent.

This case goes a bit further, and gets at whether an organization is liable for libel or slander, or is guilty of racketeering or similar crimes, if it tries to harm your private life or business outside the organization. There's not enough information in this article to determine whether for instance the expelled member's business is patronized primarily by members of his church, or if there's a broader conspiracy to smear him with the general public.

I do not think that churches or private member organizations should be exempt from any laws relating to quantifiable civil harms. There are pretty clear laws against racketeering, libel and slander. If these or similar harms have been committed against the plaintiff, then he's entitled to relief, if the evidence supports his claims.

But then, many laws don't get enforced when it comes to churches. The Johnson Amendment here in the US prohibits churches from endorsing political candidates, on penalty of losing their tax exempt status. It's never been enforced. The IRS made a half-hearted attempt once, and backed off. The only case of any note where tax exemption was revoked was the Church of Scientology, and they managed to get that reversed, even with their egregious abuses of power and overt criminality.

So unless the law and political will are different in Canada, I'm not holding my breath for this guy to get satisfaction, even if his claims are legitimate.

Firstly, I have at least 2 regular customers who are JWs and know that I am an atheist. Secondly the guy was kicked out for being a drunk who verbally abused his wife. Now Im not defending the JWs here but the decision not to do business with this guy might be one that any of us might take.

Confusing

Not sure about Canadian jurisprudence but in the U.S. if you are harmed and can prove damages you can sue anyone, anything. In the U.S. it would be called interference with business relationships and if it caused someone to break a contract of some sort with the "shun-ee" I don't know it couldnt work. Here are the elements:
Third-party Intentional Interference Claims
In regards to any commercial litigation, intentional interference with a contract is a typical example of a third-party interference claim. Usually, for businesses, it could be the competition or even potential competitors who are committing this tort. Intentional interference with contract arises when a person intentionally damages the plaintiff’s contractual or some other business relationships. Intentional interference with contract may also occur when a third-party tortfeasor persuades a party to breach the contract with the plaintiff, or where he intentionally disrupts the ability of one party to satisfy his obligations under the contract, thus, injuring the plaintiff. In order for there to be an interference with contract claim, there needs to be a valid contract that is already in existence.

In an action for intentional interference with contract, a plaintiff must allege:

The existence of a valid and enforceable contract;
Defendant’s awareness of the contractual obligation;
Defendant’s intentional and unjustified inducement of a breach;
Subsequent breach caused by defendant’s unlawful conduct; and
Damages.