As God He can do what He wills, but if prophecy is to be fulfilled, then it required something in continuity to what was revealed throughout salvation history. An act of righteousness would not be in continuity with prophecy. In fact, we are not taught by scripture that acts of righteousness expiate sin at all. We are taught by scripture that sin required a blood sacrifice.
“For the bodies of those beasts, whose blood is brought into the holies by the high priest for sin, are burned without the camp. Wherefore Jesus also, that he might sanctify the people by his own blood, suffered without the gate.” Heb 13:11-12
So while I agree in the broad sense that anything God wills would be sufficient, it would have been ultimately incoherent if He didn’t suffer, and die on a cross.
“Christ had come in order to destroy death, not His own, (for since He is life itself, death could not be His), but men’s death. Hence it was not by reason of His being bound to die that He laid His body aside, but because the death He endured was inflicted on Him by men. But even if His body had sickened and dissolved in the sight of all men, it was not befitting Him who healed the infirmities of others to have his own body afflicted with the same. And even had He laid His body aside without any sickness, and had then appeared, men would not have believed Him when He spoke of His resurrection. For how could Christ’s victory over death appear, unless He endured it in the sight of all men, and so proved that death was vanquished by the incorruption of His body?”
-St.John Chrysostom