Hitler was a charismatic leader, an inspirational speaker (i.e. he did know how to inspire people to action), and also a sociopath, drug addict, and obsessed with the occult and power (and in particular, how the occult could increase his power). He was a megalomaniac. I agree with Marge in the sense that anyone who can look at Hitler with any kind of awe and inspiration after knowing what his ends were makes me cringe. Jim Jones was also a charismatic leader and inspirational speaker...but people don't look at him with awe and inpiration now, knowing what happened in Guayana.
I'm taking a leap here, but I think what Marge is trying to say is that the distance from WWII is, in general, getting large enough that younger generations view it in much the same sense as we view the Civil or Revolutionary Wars. They are interesting to study, but there isn't a personal connection for the majority of people. Of course there will be exception, such as Leli has pointed out as her own personal experience. But the fact that the WWII veterans are dying at a rate of hundreds or thousands a day now simply because of their age, the people personally affected by it are becoming fewer and fewer.
What does this have to do with this kid? Well, because the people affected by his actions are not prevalent, Hitler is more and more becoming idealized. The horror of what he put not only the Jewish/Gypsy/disabled/retarded people through, but also his own people through, is becoming lost in the historical "facts and figures". So there are people who are disillussioned with society today and look to the past for ideals, and find there Hitler and Stalin. And their ideology and people who subscribe to it are readily found on the internet, and the results, such as Columbine are plastered all over the media for years (think it was bad nationwide? Try living here! It was on nearly every local news broadcast for at least 2 years, at least once a week). All of that plays into the vulnerability of a kid who is lost, bullied, angry, and hopeless...regardless of how he dresses or what music he listens to.