They have no experience in this. They should have been taking over / buying out an established altcoin or just use BTC blockchain.
They could do that or they can just experiment with open source software and build something of their own. They aren't stupid. It's actually quite cool that a bank is creating coins and testing it out. It means progress is happening in some form or another. They will never touch Bitcoin probably, too much uncertainties in their mind. We know better