Perhaps you are mistakenly literally interpreting the stories about him, and that he truly was not literally, physically in a Turkish penal colony? Rather, he was only mentally imprisoned because he was not able to profess all that he knew and understood?
You could check that out for yourself…I’ve visited the cell where Baha’u’llah was imprisoned in the prison fortress of Akka…but here are the words of Abdul-Baha on the subject:
*When Bahá’u’lláh arrived at 'Akka, through the power of God He was able to hoist His banner. His light at first had been a star; now it became a mighty sun, and the illumination of His Cause expanded from the East to the West. Inside prison walls He wrote Epistles to all the kings and rulers of nations, summoning them to arbitration and universal peace. Some of the kings received His words with disdain and contempt. One of these was the Sultan of the Ottoman kingdom. Napoleon III of France did not reply. A second Epistle was addressed to him. It stated,
**“I have written you an Epistle before this, summoning you to the Cause of God, but you are of the heedless. You have proclaimed that you were the defender of the oppressed; now it hath become evident that you are not. Nor are you kind to your own suffering and oppressed people. Your actions are contrary to your own interests, and your kingly pride must fall. Because of your arrogance God shortly will destroy your sovereignty. France will flee away from you, and you will be overwhelmed by a great conquest. There will be lamentation and mourning, women bemoaning the loss of their sons.” **
This arraignment of Napoleon III was published and spread.
Read it and consider: one prisoner, single and solitary, without assistant or defender, a foreigner and stranger imprisoned in the fortress of 'Akka, writing such letters to the Emperor of France and Sultan of Turkey. Reflect upon this: how Bahá’u’lláh upraised the standard of His Cause in prison. Refer to history. It is without parallel. No such thing has happened before that time nor since–a prisoner and a exile advancing His Cause and spreading His teachings broadcast so that eventually He became powerful enough to conquer the very king who banished Him.
His Cause spread more and more. The Blessed Perfection was a prisoner twenty-five years. During all this time He was subjected to the indignities and revilement of the people. He was persecuted, mocked and put in chains. In Persia His properties were pillaged and His possessions confiscated. First, there was banishment from Persia to Baghdad, then to Constantinople, then to Adrianople, finally from Rumelia to the prison fortress of 'Akka.
*
bahai-library.com/abdulbaha_royal_family_description