the bill in consideration was only aimed at companies taking TARP money. It wasn't universally applied to the entire population of bonus earners.
The "wealth tax" is not an attainder. It is a "land grab" that falls in that spirit..but as its NOT a complete confiscation it could very well pass constitutional muster.
Want to make it even more palatable? Make it a 35% immediate tax and for anyone paying that tax, forgive that estate of any further inheritance tax.