It's a fairly simple answer. Stay at 16 in the clear and full speed to Atlanta. You won't lose any time and maybe burn 10-20 gallons extra. You can always go higher further south if it opens up. The TBM will do that easily and be at 100% torque and not much less than max speed at 16.
With a dog (that may be unrestrained), family and an associate in the plane, turbulence and ice can be distracting, my initial reaction would be to stay away from anything that is going to cause concern in the back. A clear sky at 16,000 listening to ice reports above is a nice, low-stress place to be. Why place yourself in a high-anxiety situation if you don't need to?
Operationally, for visible moisture the POH says deploy the inertial separator which the video says was OFF at the scene. Anyone concerned about ice would have all that stuff ON before punching upwards. From level cruise, the TBM can jump through a 2000 foot layer of stuff at 3000-5000fpm and be finished with it in less than a minute. I can't recall the last time I had appreciable accumulations on the TBM but I certainly can recall many occurrences on the pistons.
This accident scenario has never made any sense to me no matter how I replay the events especially the low airspeeds and groundspeeds shown during the event. But, I've seen videos from cameras placed inside the cowl of the TBM during icing and if the Separator is not ON, ice can accumulate inside the cowl and choke off the inlet to the PT6.