The first problem I see are the technical issues and many debates that flare up from time to time over the definition of "what is a last name". Did you consider the fact that some people store author as "Lastname, Firstname"? Or issues with names from other languages?
However the other issue I would suggest is that I don't see the use case for it?
The only situation that this functionality is presumably being used is when you are trying to find variations of an author's name to do a cleanup of your database. However there is a plugin that will do a better job of this already - Find Duplicates. Use that with an "Ignore Title, Similar Author" search to find your author variations, get them fixed, and from that point on the built-in Alt+A search will do you just fine. The other bonus of Find Duplicates is that it should find variations of combinations of the author names where the ordering may differ etc.
Just my 2p, but I have no say on what goes into the codebase so you can take that for what it is worth
