No, så is a word of its own. English can use "such" in basically the same sense as "so" here, but Swedish sådana doesn't quite work as a substitute. You'd be understood but people would think it sounds quaint, or off.
Does nobody else think the audio sounds like "varför har han så långa armar"?
You're right, it's definitely wrong. I'll turn the audio off for it, so people don't get marked incorrect during "type what you hear" exercises.