Ah...
yes , let's see if I can be a bit more coherent today.
so basically the long and the short of it is,
I think that imakarum sees a need for archanphel to understand what human nature is. archanfel never had any social bonds,he was made as a general. he wasn't given a family and a society. he doesn't understand what shou stands for. so I believe that putting tetsuro and mizuki in the cabin with archanfel, may lead to some form of social bonding.
archanfel must be feeling very hurt by his 'parents' leaving him behind. he must be very hurt.
perhaps by living with the segawas and perhaps bonding with them on some level will give him and understanding of humanity and perhaps change his approach.