Well, there are lots of positives in this. Your friend is recognizing that demons are a problem that require spiritual help to defeat. Even though he may not intend to take out the bottle, it is there if he feels threatened by the demonic.
Your friend, by his request, has also recognized that the Catholic Church has something that his Church does not and that the Catholic priest has power to confer spiritual power on water, that is effective against the demonic. He has recognized that holy water is different and special and this may lead him closer to the fullness of truth. He has also recognized that a Catholic priest has powers that a Protestant minister does not.
If he does open and use the holy water, this will be of great spiritual benefit.
Yea, I’m thinking “Teaching moment” here for the Baptist friend of the OP.
Explaining why priests can bless, because they have gone through the sacrament of Holy Orders, and where the sacrament of Holy Orders is in the Bible…
For this reason, I remind you to stir into flame the gift of God that you have through the imposition of my hands. For God did not give us a spirit of cowardice but rather of power and love and self-control. (2 Timothy 1:6-7)
The sacrament confers power on the priest, as communicated very clearly by Paul to Timothy.
God may be presenting us with a great opportunity here. It may do us well to discern a well placed, gentle question to the man who wishes to hunt demons, such as, “I’ve wondered why you think holy water will help against demons?”
I know a guy who was a Charismatic Protestant, who happened to be in a Catholic Church one day for a wedding or some other function. The priest overheard him mention that he was charismatic, introduced himself, and asked if he would like to see the Church’s “Healing oils.” He took him to the sanctuary where the oils of annointing were stored in a display cabinet, and the Charistmatic Protestant was blown away. He had no idea that Catholics had “Healing oils.” Dude’s now a 4th degree Knight of Columbus
I have become all things to all, to save at least some. (1 Corinthains 9:22)
My point is, the OP shouldn’t be so caught up in whether it was a sin or not. Yea, go to confession, but go with the Holy Spirit too, talk to the Demon Hunter, ask questions, invite him to Mass, and see where it leads. Meet the guy right were he is. If it’s not God’s will, then so be it. But who knows?
-Tim-