I probably got a little too animated expressing my opinion, but it is a way I feel. They could have hired someone to play a live harp, or just asked a friend (even I have a friend who plays harp). And then wrote their own harp parts and had them performed. Relying on instrumental sample packs feels like a cheap crutch when there are humans available to perform those parts... or even sample libraries like Colossus, or any number of VST options. But the main difference is that Mr. Korb probably did have access to VSTs or musicians, but chose to "write" with the pre-made song sections instead.
Maybe I'm crazy. Maybe playing instruments and being part of OCR, a site that frowns upon verbatim source usage or sampling the original song, contributed to how I feel about this kind of sampling.