Did Satoshi ever mention anything about the taxing of Bitcoin?
I think satoshi never thought of bitcoin being used on a mass global level so there was no chance of him mentioned anything related to the taxes on bitcoin. The taxes are government specific and every government has the right to put different taxes on the transactions of bitcoin. But for this to happen, they will have to make bitcoin legal first.
The first part of your statement is wrong. You can check the posts that Satoshi made in this forum during 2010 and it is clear that he wanted BTC to grow as a trans-national currency. That said, it is true that he didn't mentioned anything about the taxation, either in the forum posts or in the original Bitcoin white paper (which was published in 2008).