He thinks if Michael doesn't want to help than Wanda easily will, but that's a different thing that needs to be considered.

"That symbol you told me about on the shrines, has anyone told you about that, yet?"

He'll get the information from Sam's domain eventually, but, well, they're talking now.

Maybe if he pumps Istredd's brain full of enough knowledge his brain will shut up about everything else and he'll sleep better, as though it wasn't Lucifer to be the one to wake up this time.