What I thought he was saying: "Are you saying we should get his signature now while we still can!?"
I was stuck for several days on this sentence having trouble making sense of it, suspecting that there was some contraction I was having trouble with. I suspected that もらっとけ was a contraction of もらっておけ but wasn't sure where else to go from there.
I was also wondering is what is the grammatical meaning of having the form ておけ here, instead of ておこう or something? I've noticed that other questions like this one mention the ておけ form but doesn't really explain why the sentence uses that form specifically.