Ok so i didn't read the entire thing but let me point something out. It says in the bible that you should deal with paranormal and the dead. Leave the dead dead as they are separated from the living for a reason. Now of course this isn't exactly what it says and i can't remember what verse it was but that could be part of his reaction.
I found some verses such as
Leviticus 19:31 Do not turn to mediums or seek out spiritists, for you will be defiled by them. I am the Lord you God.
Leviticus 20:27 Men and women among you who act as mediums or psychics must be put to death by stoning. They are guilty of a capital offense.
1 Chronicles 10:13-14 Saul died because he was unfaithful to the LORD; he did not keep the word of the LORD and even consulted a medium for guidance, and did not inquire of the LORD. So the LORD put him to death and turned the kingdom over to David son of Jesse.
Not sure if this answers what you are asking but it should help
I guess it kind of helps? All i'm getting from that (mind you I'm no expert in interpreting the bible, or whichever scripture that's from) is that yeah it makes sense you can't watch watch horror movies with demons because it will defile you; but then wouldn't playing a video game defile you too? They might be animated, but theres still spirits and ghosts/demons, Undead, and even references to the bible.
And going into playing those games, you know theres undead, demons, etc... so why is it okay to play THAT game in your head/faith/mindset/whatever, but not okay to watch horror movies?