Renate,
I think that, regardless his tact and lack, that the person who wrote you the memo is within legal rights on this. No one can make them set a new policy without some court-backing is I think what he meant to say. *smile*
But, if he is far away and outta mind for the people you work with, you may find that they are much more accepting and will not rock any boats, at least not publicly.
Just a wild guess, but he prolly read your memo as an ultimatum and was thinking, "o, this is gonna be a real pain-in-the-tush." So, I need to be very firm." He was prolly thinking "lawsuit' and just wanted you to know that there was no legal requirement that anyone calles you by the pronouns that you wish unless you are adjudged 'female' in a court-of-law.
Nichole