It's not just the upload being powerful that made it magic, it was also the fact that the technology wasn't even internally consistent. None of its powers or limitations were derived from anything scientific, it was just a complete mess wearing the attire of science. I call such a mess "magic".

Stuff like:

• Despite the untested and jury-rigged nature of the upload procedure, the upload managed to rewrite and optimize itself (rather than just editing itself to insanity) almost instantly after being uploaded. Just a few moments after that, it became capable of playing the financial markets so as to give itself millions of dollars as well as hacking pretty much every computer in existence. Even though the original AI system that it was uploaded on had never shown any signs of being capable of anything like that. Even when the original system had had many times as much computing power at its disposal (they uploaded the scientist on just a couple of computing cores stolen from the original system).
• The upload had two years after that to continue rewriting and optimizing itself, but someone who had the "source code" to the original AI system could use still use the source code to write a virus that would disable the upload if the virus was just delivered right. When they guy couldn't even have known whether the upload was still running on any of the original source code or whether it had all been rewritten.
• The same virus could also somehow disable pretty much all technology on Earth while it was at it.
• For all its hyper-technology and ability to precisely scan the physiology of another person, the upload completely failed to develop its abilities when it came to emotional intelligence. Develop arbitrarily advanced medical technology? Sure! Figure out the basics of social understanding that would allow you to know when you were doing stuff that would completely freak out your wife? Unpossible!
• The AI might have nanotechnology that gets all around the planet as well as enhanced superhuman cyborgs in its employ, but build an underground Faraday cage and you'll be protected from most of its attempts at attacking you. (I forget the details, but I seem to recall that the cyborgs were pretty much entirely disabled if brought to the cages.)