I don't know. Some other countries have this exception, i.e. you can travel on, while not finishing quarantine, but this doesn't mean anything. This thread is already full of interpretations of rules according to personal preferences, I wouldn't want to add another one.
I guess, the only one able to answer those question are cantonal authorities, the contacts are in one and only link:
BAG entering Switzerland
Description of possible exemptions are so broad that I think they cannot be easily just self-proclaimed, but I also don't see that transit is limited to non-Swiss residents or not entering Switzerland. Than it wouldn't be a transit exception?

The one in Italy!

Tom