From the linked picture:
"air entered the tube, burning in a purple color, slowly replacing the Argon/Neon/Mercury mixture in blue"
I don't see an analogy. Why should a germicidal lamp be the same as this mixture?
Has anybody actually seen that?
Because in both the main radiating element is the mercury, second in line is argon, none of them has any color conversion.
The fact the Neon tubing does not allow the UV to pass does not afect the color, as UV is not visible (the long wave UV, which is slightly visible, passes even the clear glass of the "neon" tube, so no difference either)...