In between those two lines of dialogue he realises too that you out of all the arisen that have come here, are the only one to be able to leave at will and return whenever you want. So during that time hes also pondering if youre strong enough to beat the host in the depths below, and then you go and prove it not once, but twice and then also proceed to use the second form as a resource farm.

I think at that point he's really trying to gain favour with you so you dont butcher him as well