According to my knowledge the exclusion principle won't affect it, so it will jump to the muonic 1s orbit (strongly deformed by the electrons' repulsion). The electrons fill the electron 1s orbits (also distorted). So it would become like a He, but much heavier and easier to ionize.
It seems like my answer is correct. So repost:
So because electron-nucleus and muon-nucleus bond are on different energy scale, the problem can be separated into two parts: The muon would see a nucleus with 3+ charge in a large negative change-cloud. The electrons would see a 2+ charged nucleus. After 2us the muon decays and its energy blows away all two electrons.