It took a long time, but this Reimu finally became a true Deibu; nothing says Deibu more than putting your family at risk, because of superficial fears.
Not so much, it's proving that anon knew what he was doing all along; ie that he knew there were kids when before he feigned ignorance.
(Also, I rather question how "superficial" her fears are; and observe that, given a similar situation, even humans might act in a similar way... Especially if they had reason to think that Mister was lying.)
I meant superficial as in her treatment of the remi koyukkuri. The sins of the father don't transfer to the son.
Also, this anon gave them a week's supply of food, and even medicine when they wanted it. He stated that he only wanted her to take care of the remi koyukkuri until they could fend for themselves. She's indirectly killing her family by pissing anon off.