Maybe the owner of the cold wallet that will contain (on the old chain) all the BTS tokens collected ??

I'm not sure but supporters will not hold BTS token on the new chain litterally. Supporters will give their BTS token to 'BEOS team'. And they will receive BEOS token in compensation. With the assurance that they will have the possibility to exchange BEOS at any time against their original BTS. Like Openledger is doing with your real BTC in exchange of OPEN-BTC and viceversa.

That's the way i see things from my understanding of this interview.