The problem with this view (even though you could be right) is that what you are stating is unfalsifiable. Nothing - no words and acts of contrition, for example - could ever count against it, and may indeed be interpreted as further indications of someone's deviousness.
On the other hand, if we were to take those selfsame words and acts at face value, we might be incorrect to do so.
A good example is the famous case of Leopold and Loeb, who were both guilty of the horrendous and premeditated murder of a teenage boy for the most heinous of motives.
en.wikipedia.org
The section on Leopold's post-prison years is instructive. Perhaps it demonstrates that people who do the very worst things can lift themselves out of a moral sewer by their subsequent actions.
However, it may also be possible to summon up arguments in support of the view that what Leopold did was so beyond the pale that he should have received the death penalty. Clarence Darrow, the famous defence attorney - successfully and famously argued against that position, though.
Another factor to consider is that there is a world of difference between the brain of a 15 year old adolescent and that of a fully developed adult:
"It doesn’t matter how smart teens are or how well they scored on the SAT or ACT. Good judgment isn’t something they can excel in, at least not yet.
The rational part of a teen’s brain isn’t fully developed and won’t be until age 25 or so.
In fact, recent research has found that adult and teen brains work differently. Adults think with the prefrontal cortex, the brain’s rational part. This is the part of the brain that responds to situations with good judgment and an awareness of long-term consequences. Teens process information with the amygdala. This is the emotional part.
In teens' brains, the connections between the emotional part of the brain and the decision-making center are still developing—and not always at the same rate. That’s why when teens have overwhelming emotional input, they can’t explain later what they were thinking. They weren’t thinking as much as they were feeling."
Here is a link to the full article that I have just quoted from:
www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=3051#:~:text=The%20rational%20part%20of%20a,cortex%2C%20the%20brain's%20rational%20part.
One last thing that I worry about when I read your posts is a lack of epistemic humility that I detect in them.
The only way to know for
sure whether Begum knew what she was doing would be if we had knowledge of other minds.
But none of us possess this ability.
