The real answer to the hot spring question is here!
The person who asked this question has posted
his recording of this question himself on Youtube, and the audio in this video is very clear.
Here's the important part, transcribed by
Five Ants, one of the most knowledgeable Japanese fans:
ZUN「まあ考えたけどやっぱ変なキャラクターいるわけにいかないので 霊夢と魔理沙でお願いします」
司会者「やっぱりビールももちろん皆さんで飲みますよね?」
ZUN「もちろん」
Translation:
ZUN: "Well, thinking about it, it can't be the weird characters after all. Please let it be Reimu and Marisa then."
Presenter: "It goes without saying you are going to drink beer together, right?"
ZUN: "Of course."
Japanese fans tend to read it as saying "of course there's nothing wrong for a father to bath with his daughters" (back when all Japanese bathe in public baths with no gender difference, this is normal ).
Five Ants, on the other hand, has made an interesting
reading when only the answer "Marisa" was known: "in the case of Marisa, a human was chosen for personal safety."
What Five Ants meant was, ZUN doesn't think of Gensokyo as a place for himself to live in. He's only an ordinary human from outside; no special treatment awaits him in Gensokyo, and the youkai will find him to be easy food all the same. So he should choose humans.