Romans 5 a ProofText for Universalism?

Recently a poster over Steve Gregg's forum, using the handle "Homer," suggested (it seems, he was a bit oblique) that if Romans 5 demonstrates Original Sin, that it also is a "prooftext for Universalism."

I had written: "Calvinists affirm what Paul taught in Romans 5, that Adam's guilt was imputed to his family, just as Christ's righteousness is imputed to his family."

Homer responded that perhaps my statement seemed right when Romans 5 was "read through [a] Calvinist lens," but then went on to claim that if Romans 5:12-15 and 18-19 are talking about spiritual death, then we have a "proof-text" for Universalism.

Before my answer, here is a reproduction of the passage (Romans 5:8-21):

Romans 5:8-21
8But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us. 9Much more then, being now justified by his blood, we shall be saved from wrath through him. 10For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life. 11And not only so, but we also joy in God through our Lord Jesus Christ, by whom we have now received the atonement. 12Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned: 13(For until the law sin was in the world: but sin is not imputed when there is no law. 14Nevertheless death reigned from Adam to Moses, even over them that had not sinned after the similitude of Adam's transgression, who is the figure of him that was to come. 15But not as the offence, so also is the free gift. For if through the offence of one many be dead, much more the grace of God, and the gift by grace, which is by one man, Jesus Christ, hath abounded unto many. 16And not as it was by one that sinned, so is the gift: for the judgment was by one to condemnation, but the free gift is of many offences unto justification. 17For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ.) 18Therefore as by the offence of one judgment came upon all men to condemnation; even so by the righteousness of one the free gift came upon all men unto justification of life. 19For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous. 20Moreover the law entered, that the offence might abound. But where sin abounded, grace did much more abound: 21That as sin hath reigned unto death, even so might grace reign through righteousness unto eternal life by Jesus Christ our Lord.

I answer:

a) Both do refer to spiritual death.

b) They are only a "prooftext" for universalism to the extent that the "many" to whom the grace of Christ has abounded (in verse 15), the "all men unto justification" in verse 18, and the "many" that shall be made righteous (in verse 19) are co-extensive with the "all men" in verse 12, "all men to condemnation" in verse 18, and the "many were made sinners" in verse 19. If, however, (as we would suggest) the latter group is all in Adam (i.e. Adam's family) and the former group is all in Christ (i.e. Christ's family), then there is no reason to reach a universalist view from the text.

c) But let's go a step beyond. Could they refer to physical death alone? How could God permit an innocent man to die (even purely physically) without imputing sin to that person? For whose sins do infants die?

-TurretinFan