Can a mentally incompetent defendant defend himself in a civil case?

It is true Massey v. Moore and like cases arose in the context of criminal proceedings. Nonetheless, they articulated minimum standards demanded by due process--a clause which applies to civil as well as criminal cases--not the Sixth Amendment which applies only to the latter. If it is not merely difficult but impossible for a mental incompetent to defend himself without counsel in a criminal prosecution, it is just as impossible for him to do so in a civil case. And, even if due process eventually can be twisted to somehow tolerate imposing on normal poor people the difficult task of defending their property rights in the courts without lawyers, it can never be so stripped of meaning as to foist that task on those for whom it would be an impossibility--mentally incompetent poor people. That is tantamount to sanctioning legalized robbery--using the coercive power of the state to force defenseless people to surrender their property without a meaningful hearing.