Responses
I'm pretty sure even if Blast got a hold of power through space, I don't think he can understand the concept of time and realize that Saitama went back to time. (I'm not really sure, I'm puzzled by my memories.)
If my memory serves me right, I believe Blast also forgot about the whole turning back time matters, same like the everbody else sans Genos's core and as of now, he might has seen Saitama as your general Hero, or maybe one of S class heroes. He hasn't yet to witness that otherworldly power of our Caped Baldy, cmiiw.
Does blast acknowledge Saitama's power?
I mean he saw how Saitama managed to turn back time and shit right? Holding that orb. Does he acknowledges it or is he turning a blind eye?