The treaty of London, under which Otto was accepted as King of Greece, stated that under no circumstances the crowns of Bavaria and Greece would ever merge.
This means that if Maximilian II had had no heirs, should Otto have kept his greek crown he could not have succeeded in Munich and the crown would pass to Luitpold and his successors.
The problem would raise when Otto died in 1867.
Who would have succeeded him ?
His two nephews Ludwig II and Otto were not married nor had children.
Luitpold would have to opt between the bavarian or the greek crown and in 1867 his nephews' insanity was not that evident.
Would he have accept the greek crown and the bavarian crown pass to the younger brother Adalbert ? Or would he relinquish the greek crown in favour of Adalbert ? And would the greek accept this "farewell, I'm leaving to Munich but I leave here my brother" ?
Too many "If's".
I know this is not answering your question but for me it raises the question can one renounce or give up something that you have not got. Legally could Otto renounce the Bavarian throne, which he did not have, for descendants he did not yet have? This applies to all renunciations. If a royal looses their rights because they make illegal (either through the law of the land or family law) marriages then I can see how they forfeit their rights for themselves and their descendants, but to renounce the remote possibility of something seems to me to be wrong. Can one give up something for someone who has not yet been born? A difficult question I think.
Did he formally renounce, for himself and all hypothetical descendants, claims on the Bavarian throne, upon accepting the Greek? If so, was the said renunciation of rights in writing? Are there documents in proof of this?