Let us test your premise.
I catch on video a man entering my house and taking a bag of money I own which contains 1000 bucks. (I have a positive ID)
Law enforcement tells me there is nothing they can do because of some legal loophole.
So then I enter his home and take 1000 bucks. Am I guilty of stealing?
I state that fair debts should be repaid and that scheming to do otherwise is thievery. You reply by asking me if I approve of vigilante justice.
Perhaps I should answer by asking if you approve of burning puppies to keep the house warm.
But I'll oblige your question, although it has no bearing at all on whether choosing to renege on just debt is thievery. The answer is, retaking possession of my own property is not stealing. Further, justice is not defined by the limits or enforceability of the law, no matter whether you gain or lose by the inadequacy of the legal system to deliver justice.