If I told you about a suburban college educated CD that flipped from Romney +4 to Clinton +12, it would be safe D in a landslide according to Atlas, and Atlas would be right. Based off everything we know as of now (ie, no anti Trump mega landslide) Safe R is the similarily only realistic answer here
The problem with that logic is that it isn't supported with numbers. There are a number of Romney to Clinton counties that maintained some of the swing in elections after 2016, but the same cannot be said of Macomb County. If it was Safe Republican then Republicans would have carried it in 2018 even while losing statewide.
In 2008, Obama flipped Dallas County for the first time in a generation. In 2010, it went red in the statewide races. Should we have interpreted this as evidence it would vote for Mitt Romney in 2012, or that Democrats did badly in a blue county in a red wave?
Seeing as Dallas County voted for all Dems except for the LG candidate (and by a fraction of a point) in 2010 and went 55-42D for Governor, yes, it would have been very Safe D
Ah, my apologies. For some reason I was thinking of Bexar County in my head, which did go blue in the Governor race but stayed red other than that. My bad!
Getting your words mixed up doesn't make the poor logic behind them any better.