A defense against a criticism of "Faithfulness of Jesus"

Preamble:  A growing number of scholars are interpreting Paul's quotation of Habakkuk 2:4 in Romans 1:17 Christologically, that is, Romans 1:17 should be glossed something like:

For the righteousness of God is revealed in it from [Christ's] faith[fulness] to [our] faith[fulness], as it has been written, "but the righteous one [i.e. Jesus] by faith[fulness] will live [i.e. have resurrected life]".

Criticism of Christological interpretation:  One criticism of the Christological interpretation is that it turns Romans 1:16-18 on its head [see Charles Quarles].  If Christ achieved eschatological life by his faithfulness then given that Paul says that Christ was born under the law it would seem to follow that the righteous are those who observe the law and this runs counter to Paul's sustained argument in Romans 3:19-4:25.

Answer to criticism: I intend to show that this criticism is weak by giving an account that actually reinforces the Christological interpretation.

Without argument I claim that Paul held to some such argument:

• Those who embrace the works of the law are identifying with Israel-as-a-whole.
• The law promises the curse (ending in death) for Israel-as-a-whole, if they do not observe the entire law.
• Israel-as-a-whole have failed to observe the entire law.
• Therefore, Israel is under the curse (ending in death).
• Therefore Gentiles ought not to embrace the works of the law.

The problem with the law is that it sentences disobedience with death. This is particularly clear in 2 Corinthians 3:

• Verse 6: the letter kills, but the Spirit gives life
• Verse 7: the law is a ministry of death
• Verse 9: the law is a ministry of condemnation 

Whatever Paul thinks of the Christ event, he clearly thinks that it is "apart from the law" (Romans 3:21).  If this is Quarles' quarrel then I think his beef is with Paul for Paul has detached faithfulness or fidelity from law observance in the cases of both Abraham and Jesus.  In the case of Abraham the point can be made temporally: Abraham evidenced fidelity before he observed any work of law.  In the case of Jesus Paul seems to think that Jesus' chief act of fidelity (death on the cross) was outside the law in that the law curses anyone "hanging on a tree".  Better, the law as an entity had run its course with the advent of Jesus (see Romans 10:4).  Paul's main point is that the Christ event (but not the law) inaugurated the new covenant which brings obedience (law written on heart) and with it life.  Therefore, it makes perfect sense to argue that Romans 1:17 ought to be interpreted Christologically.  Jesus' faithfulness on the cross did lead to his resurrection and to all his faithful followers' eschatological resurrection!