Yes, I know, as I said, for exchanges this is a loose-loose-loose game. If you decide today to support SegWit2x, some customers will leave. If you decide today to not suppoprt SegWit2x, some customers will leave. If you don't decide, some people like you get upset. Sorry for this.
TBH I don't know what Bitcoin.de will do in case of a "contentious" hardfork to SegWit2x. I guess - and hope, but can't promise - that if the clear majority of hashrate is on the side of SW2X and it is clear that it is not the Core phantasy of "rogue miners rebelling against economic majority", that this will be BTC. But deciding now what BTC will be, is just reckless against the customers.
I'm aware that there is some game theory mechanics with opposing incentives. It would be better for the whole ecosystem, if every exchange would clearly support SegWit2x now, but it is better for the exchanges to not do. Why do you think no exchange that did not sign the agreement has come out in clear support for SW2X? Because it is better for them (and their customers) to keep both doors open. Sorry to say this, but exchanges act in rational selfish actors or as the gateway to the rational selfish action of customers. Sometimes it is bad for the whole, if everybody acts selfish, but market theory says that it is better to let everybody act selfish. So let it be.
What Bitcoin.de does is the opposite of Luke-JRs consensus. Luke says "Le consensus, c'est moi". Bitcoin.de says: "We can't decide it, at least not now, without setting our customer's funds and our reputation at risk." Luke thinks he can force consensus, Bitcoin.de thinks it cannot and must not set consensus.