I wouldn't call him "biased". He has a strong opinion, but it's not based on nothing nor is it a product of some sort of ulterior motive. He has a strong opinion about these games that I agree with.

I had a C64 growing up so I didn't really play any of the Sierra games til I had a PC in college, and I remember feeling really confused about why people liked them so much. They felt unplayable and frustrating to me.