This may be technically possible but it may also be time consuming to implement, and and in the interest of using Fundriasing Tech time in optimal ways it may be that preserving donor anonymity from the IRS is a lower priority if the Foundation can meet its fundraising goals without doing this. I think a carefully worded, brief explanation in the blog entry and the Bitcoin donation page would be appreciated.
My personal interest in this subject isn't about bitcoin as a currency, it's about the preservation of privacy for those who want it, especially for Bitcoin if WMF is going to accept it.
I think it's reasonable for people to be surprised that anonynous donations aren't allowed through Bitcoin.
On the good side, the fact that people want to donate anonymously, taking no credit, suggests that WMF has earned some good faith even in dangerous places on the internet. That is impressive.
Pine