Here's a story that may illustrate why they (Victorinox) won't do it:
I sold kitchen hardware for 7+ years, and years ago one of our European handle (cabinet door & drawer) suppliers decided to go with a new line of custom finishes, as an aside to their regular production. They did this to try to get into a niche marker here, a niche focused on very high-end, very specialized colors, finishes, materials, etc. They thought that by offering 'production' handles with slightly different options, it would work.
Within 3-4 months, it became a nightmare. It was a neat idea, but the fact that every order was different, and sometimes only for two-three pieces, that they would have had to charge literally 20-30x regular price, just to break even. Bear in mind, these were regular production pieces, with slightly different design elements (colors, finishes, etc.)
What killed the whole concept (in seven months) was the problem of trying to keep up regular production and then create, maintain, and somehow make profitable a whole other product line, and not interfere with production already in place. Th is mfr. was using regularly produced base materials, with slightly different finishes, etc.
So, I don't mean to sound preachy, but I know from my own experience why Victorinox won't get into customs. Besides, with all the models they have or have had in the past, there's something for everyone.
thx - cpr