The way to get out of the bonds would be to launder them through third parties and beyond that try not to leave any directly incriminating fingerprints.
No doubt a lot of mainland Chinese mattresses are overstuffed with increasingly worthless U.S. notes. The Chinese have to be worried about the effects of inflation (i.e., the printing of new paper money by the Fed) on the notes. Thus the pressure to launder the equity into something of more real value.
Two possible targets for purchase by the bonds are U.S. real estate and U.S. politicians.
If I were the Chinese, I would get third parties comprised of some kind of convenient non-Chinese nationality with experience in business and travel, but usually beyond suspicion (e.g. Japanese) to help launder the bonds.
I am still a bit puzzled in that using Switzerland does not seem to me to be as obvious a choice as the Caymans or Bahama for this type of stuff. Perhaps the target purchases for this particular operation are not so much in the U.S. as in places such as Spain, Portugal, Greece, etc.
One way or another I anticipate that Chinese influence and power is expanding rapidly and quietly via this type of operation.
Ordinarily there aren't border checks between Switzerland and Italy, unlike the rather through checks you get arriving at international airports. If they were just going to stash them in a safe deposit box, then Switzerland is a better choice.