I don't unsqueeze the footage in Resolve, I do it in MLVApp. Let's say, I have filmed the footage in 1736x2928p resolution. I import it in MLVApp, unsqueeze it, make all necessary corrections, sharpen and export it in ProRes as a 5208x2928p file. I open this footage in Resolve, do the editing, mounting, etc. and then I downscale it to my final desired resolution - say 1920x1080. That's all. The reason why I export in ProRes 5208x2928p is because I also use these files for storage - they are much lighter than the original MLVs, if I use the LT option and are also very easy to edit in Resolve. I keep the MLVs only if the footage is very important to me.
Now I understand that it is better to skip the sharpening step in MLVApp and apply sharpening in Resolve. This does not complicate my workflow, on the contrary - export of unsharpened footage from MLVApp goes much faster than sharpened one.