From the CDC:
"For Whole Cuts of Meat (excluding poultry)
Cook to at least 145° F (63° C) as measured with a food thermometer placed in the thickest part of the meat, then allow the meat to rest for three minutes before carving or consuming."
Submerging a piece of meat in a water bath ensures it's that temperature all the way through. The point of cooking this way (and then searing on the outside to get a mallard reaction) is to be able to get the center to safe temp without overcooking the outer portion. I'd be amazed if the center dropped in temperature while the outside was being seared.
Just a thought...