That's not "one way of looking at it", that's literally the explanation provided by scholars of etymology. The phrase "so mir Gott hilfe" was used so often that it almost lost its meaning and people started saying "sammer gott" or even "sammer pox". It's similar as how "goodbye" is a contraction of "God be with ye".
(For clarity, the "sammer" part in "sammer pox" is not of direct relevance in any interpretation of the marginalia).
(For clarity, the "sammer" part in "sammer pox" is not of direct relevance in any interpretation of the marginalia).