No problem. Just make sure that they have properly registered you as residing abroad.
I’ve never had any German income tax or capital gains tax charged or withholding tax withheld since registering as resident abroad with German financial services providers (despite having a German tax number, too).
If you’re resident in Switzerland, you’ll be taxed here according to local legislation (that is assuming you deregistered from Germany and are not subject to exit tax, i.e. you came to Switzerland for work - not tax savings).
The secret to any great Ponzi scheme: Create good initial experiences 
Not saying they are one, to be clear. But…
Who, do you think, owns or operates the bonded warehouse?