As for his ability to defend himself, I don't see how that's relevant. Should they only sue people who can defend themselves? If a homeless guy murders you, should he just be released because it wouldn't be fair for an experienced DA to prosecute him if he can't afford to hire a really good lawyer? It's a non sequitur.
I believe the analogy here is flawed. Murder is a criminal offense and if the homeless guy didn't have the funds to retain a lawyer, the state provides one. Correct me if I am wrong, but I don't believe the state provides a public defender for civil cases.