I agree with the possibility that the frame was clamped in a vice or a work stand of some sort (my money would be on a work stand as most vices would leave a different pattern.
Is the frame safe to use? That answer would fall into the 50-50 category or, stated differently, perhaps or perhaps not. If the frame were mine, I would not want or ride it. The cosmetics are not to my liking, because of the dents and I would never be able to ride the bike with peace of mind, being always concerned that the frame would buckle up and cause a crash.
Appraisal? For the components fitted, $150 to $200. For the frame itself - $0.00 (I just would not want it at all). But that is just me and my opinion on damaged frame sets.