Rom 1:16-19 For I am not ashamed of the gospel of Christ, for it is the power of God to salvation to everyone believing, both to Jew first, and to Greek; for in it the righteousness of God is revealed from faith to faith; even as it has been written, "But the just shall live by faith." (Hab. 2:4) For God's wrath is revealed from Heaven on all ungodliness and unrighteousness of men, holding the truth in unrighteousness, because the thing known of God is clearly known within them, for God revealed it to them.
Who is the 'them' in vs 19? Those "holding the truth in unrighteousness". That's not the world at large, or any subset of it.
Again:
Rom 2:14 For when nations not having Law do by nature the things of the Law, they not having Law are a law to themselves,
Rom 2:15 who show the work of the Law written in their hearts, their conscience witnessing with them, and the thoughts between one another accusing or even excusing,
Rom 2:16 in a day when God judges the hidden things of men, according to my gospel, through Jesus Christ.
Who's "conscience" is witnessing with them? Those of the nations not having Law.
As far as those individuals who are unable to make moral choices, as in a lot of things, the absence of a function helps to solidify the understanding of the function. An example would be something I am unable to do. I'm partially color-blind. No amount of 'education' can make me see certain colors. But the 'study' of color-blindness has helped in the understanding of "normal" color vision. Maybe there is a spiritual application to that regarding your question. Then again, maybe not.
Rom 2:6 ''TO EACH MAN HE WILL MAKE AN AWARD CORRESPONDING TO HIS ACTIONS''
Rev.20:13 ''...And they were condemned, each in accord with their acts.''
Correctomundo.
And to add: 2Co 5:10 For we must all appear before the judgment seat of Christ; that every one may receive the things done in his body, according to that he hath done, whether it be good (things) or bad (things).
Parentheses mine.