Whao.. hold on there a little ...'Earth's Mightiest Mortal'!
3. No one has said 'when' a subject fails if they can possibly know about that until they are ...out in the world and make choices of what to do with their powers. It could be just as true that Mary worked for a time but something happened or she found out what she wanted was not what she NEEDED... and became despondent and that is what turned her in her grief into what she became the "gift" might not have done anything to her that she did not expect... but it still might not have brought her the happiness she sought. Oft times what people think is best for them and what they think the need are only wants and not truly ... necessarily what they ACTUALLY need!
Also, his bargain is to give them power... he did not say,
"you can only use it in a way I Deem appropriate..", no one would accept power on those terms as they would effectively be agreeing to be his slave. Thin Man has to let them do as they will with it. It IS THEIR choice to use... or sadly ABUSE what he gives them. He could say otherwise and no one would accept power under those terms.
He IS in a 'hands-off' sort of way being true to the morality of the situation.
Ultimately PEOPLE are responsible for their OWN actions... to think or do otherwise is a cop-out... to avoid the responsibility or deny the consequences of one's deeds.
4. Just exactly what do you mean by this? The Thin man told Mary exactly what he was going to do to her and what it would do for her {as far as he knew perhaps}... and that he had determined though magic that this would be the best way to fulfill her ...'wants'. Her Aberrant behavior after the process is not necessarily his fault or even the result of what he did to her. He has also shown the same things to Maytag so she knows he uses magic to find suitable subjects.
Though I'm sure May will get around to asking just what he wants to do to her... but I think the more important question is WHY he desires to 'augment' people in the first place? Pure research or does he have some actual goal in mind?
5. And your point being what? That when you are looking for someone say to... try a new prosthetic limb design on, you don't search for a suitable subject first? That is just an example.. but my point being he is not trying to universally use a magical augmentation on someone not 'suitable' to the enhancement... that would be irresponsible and cruel. But the Thin Man has never claimed to know all... and surely with the power that he can apparently bestow... some people do not adjust to it well! Sort of like the sometimes referenced "Cyber-Psychosis" from the Cyberpunk Genre... but in this case its from too much magic altering ones body and mind so one has difficulty relating and perhaps even interacting with those not similarly augmented... loosing one's humanity.. and effectively their mind with it!
6. Certainly in fact his showing her this implies he did so.. he's not trying to hide this fact at all. He's just not come out and said so yet... as May has not asked.
7. Well - in fact they are. but likely even the Thin Man cannot know the unintentional side effects of a experiment. He may know what it is supposed to do.. just not ALL that it will do to a subject.
..at least THAT is how I see it. but I have no monopoly on wisdom.. lol!