Sure, but Saturn was nearly when that CoC blast happened, so whether or not he was summoned, he should be in disarray if the CoC blast was so powerful to nearly knock out the Gorosei.
We do see Saturn's face near the end if the chapter, and he's looking upon the robot with a rather neutral expression, not seeming to even be bother by the aftermath of the CoC blast.
Would still be impressive if JoyBoy's Haki was able to revert them back to their human forms, but it doesn't seem to have done much in terms of causing fatigue or damage, if any at all.