Well, that seems to be exactly my position. So I don’t understand your having to question the statement you quoted.
Whenever a person makes a true choice, that choice may have been influenced, but yet was not externally caused. For if it had been caused, then the person could not have done otherwise.
In other words, the person did not have free will.
I like the old saying that, if you’re a hammer, everything looks like a nail.
Any of us who hold dearly to a theory of some sort, tend to interpret the actions of others in terms of that theory. We don’t look for other factors or evidence, because we’re convinced of the REAL answer.
The theory of Original Sin is like that - a person who holds that theory strictly, can look at, say, the actions of a rebellious boy and conclude : he’s showing his inner sinful nature.
But in fact they boy may have been abused by his parents! Still, the theory-holder can overlook that and couch the boy’s behavior in terms of fallen human nature.
I think the same way about extremes of Will - either libertarian or determinism. If we have either of those, then ANY action will be either libertarianly free or determined. I firmly (choose to heh) think that there is a mixture of cause and effect IF we don’t look with prejudiced eyes.
Of course I could be wrong. I think in the long run we want people to hold responsibility for their actions. I agree. But certainly there is room for critical assessment of the causes of actions; making allowance for both human weakness and human victimhood.