No, not really, he hasn't. This is an 11th hour jump, that is only different from the Jeffords maneuver in the most literal and techinical sense.
So, when would YOU have him announce the change??? This is about as late into the term as it is possible to get, and still qualify for office as a Republican and run a campaign.
I still think this is about as fairly done as it is possible to make such a switch (and no, I don't think the "Phil Gramm" case is better---as it requires all the disorganization resulting from appointing a successor, having that successor take office, move to Washington, etc. etc.). The way Alexander handled it avoids all that dislocation.