God also clearly opposes the collection of firewood on the Sabbath (Numbers 15:32-36)
I presume then you must be in favour of the public stoning to death of such transgressors in your neighbourhood.
Unless of course you are the type who is happy to invoke the alleged authority of God when it coincides with your prejudices, and explain difficult teachings away when they don't.
The passage you refer to is an excellent example of why Jesus had to come to confirm God's ways and set us on the right path. In the NT there is a clear example of Jesus replacing the barbaric act of stoning with forgiveness coupled with a command to "Go and sin no more".
The passage quoted does show God giving explicit direction to Moses in a criminal justice context and is written in a historical narrative style, not some poetic or allegorical style. If we are to believe Numbers as authentic histori-scriptural narrative revealing the mind of God then you have the conundrum that faced Marcion, but because he lost the argument, modern christianity is still to this day belaboured by its OT legacy.
Moses and the OT jewish hirachy were not infallible. They made mistakes, as clearly indicated in the teachings of the New Testament.
Yes, all humans are fallible, including Moses and the other authors of the Jewish bible, including the writers of the New Testament gospels, including Paul, including Jesus, including Mohammed, including me, including you, including the Pope, even including Shaker. Oh, hang on a minute. Here's my rule of thumb : the greater an idea's dependence on a single authority for its veracity, the likelier it is to be wrong. I think it a healthy mindset to acknowledge one's limits.