That’s very difficult to say when the pasuk explicitly states that the manner of death penalty for the Shabbos desecrator was not explicitly stated.
I’m not sure what you mean by “that”. Would you mind expounding a bit?
The Torah says ” ???????????? ?????, ????????????: ???? ??? ??????, ???-????????? ???.”
The Gemorah explains in BB 119A:
????? ??? ??? ????? ??????? ????? ????? (???? ??) ?????? ??? ???? ??? ?? ??? ???? ??? ?? ???? ??? ????
Assuming Torah Chasumah Nitna, that means Moshe knew the Mikoshsh should get skilah, but was unsure if the din was “ready” to be applied, as Hashem did not yet “officially” tell him.
A similar question would have come up if a bird’s nest was found during the time the Beni Yisroel were in the Midbar. Since the Parsha of Shiluach Haken was not yet officially said, Moshe would not have been able to tell the BY to do the mitzva.