What's a Lawyer Gentleman to Do?

I just stumbled on this problem in an old ethics opinion issued by the California Bar Association:

The attorney was retained to represent a carpenter who had performed labor and supplied materials for an addition to a home. On the client's behalf, the attorney brought suit against the owner to foreclose a mechanic's lien. The action was contested and, after a trial of three days, the plaintiff obtained judgment. The defendant did not pay the judgment promptly. The attorney caused a sheriff's sale of the defendant's home to be held. Under the particular state of the law and the facts, no actual notice to the defendant was legally requisite to the validity of the sale and neither the defendant nor defendant's counsel in fact knew of the sale. The plaintiff bid in the property for the amount of the judgment, and thus became the owner of the defendant's home, worth much more than the amount of the judgment, subject only to the defendant's right to redeem within a year.

Some time later the defendant's counsel wrote a letter to the plaintiff's attorney, enclosing the defendant's check for the amount of the judgment. The check was tendered in full satisfaction, but it was legally insufficient for the redemption of the property since it did not include the expenses of the sheriff's sale, the existence of which was still unknown to the defendant and defendant's attorney.

The question presented is whether the plaintiff's attorney could properly have refrained from any action at that time, leaving the letter unanswered and the check unnegotiated, in the hope that the period of redemption would expire before the defendant or defendant's counsel became aware of the fact that their tender had been insufficient.

That's from Formal Opinion No 1967-11. So what's a gentleman lawyer to do? The opinion goes on to say:

[U]nder [former] canon 15 of the Canons of Ethics of the American Bar Association, an attorney must zealously advance the interests of his client, but not by using "any manner of fraud or chicane. He must obey his own conscience and not that of his client." One of the obligations of conscience to which the lawyer must conform is stated in [former] canon 22: his conduct with other lawyers "should be characterized by candor and fairness." [Former] canon 29 states that a lawyer "should strive at all times to uphold the honor and to maintain the dignity of the profession . . ." All of the canons are commended to the members of the State Bar by rule 1 of the Rules of Professional Conduct of the State Bar.

Yes, yes, but what's the answer?

In the opinion of the Committee, it would not have been candid or fair to opposing counsel to keep silent under these circumstances.

The interesting wrinkle is that the committee concedes it can't find any specific peg to hang its doctrine on. The committee bandies around phrases like "intentionally deceptive" and ""unjustly enriched" and "grossly unconscionable." But any firt year law student knows that "unjust enrichment" is a doctrine of almost unlimited malleability. And "grossly unconscionable" is a phrase you use when you don't have anything else.

I wonder if an ethics committee would reach the same result today. My friend Rex, who knows a lot more about this stuff than I do, says he suspects not. Yet in the bankruptcy court, where I have spent some of my (professional) life, my guess there are a lot of judges who would go ballistic if they thought someone was running this sort of caper in front of them.

Perhaps a more interesting question: if the lawyer does disclose is he breaching his fiduciary duty to his client?