Prophetic Responsibility

In 3:16-21 God describes the responsibilities of Ezekiel as watchman: Individuals will always bear responsibility for their own actions, but the watchman will share in their fate if he does not warn them, even though they will not listen. However, in v. 26 God then strikes the prophet mute in order that he “shall not be a reprover to them, for they are a rebellious breed.” Will God then hold Ezekiel responsible for not fulfilling his duties as a watchman when God Himself made Ezekiel unable to do so? How does this relate to God hardening Pharaoh’s heart? Then again, how does v. 26 fit in with v. 27 in which God instructs Ezekiel to prophecy?