Institutional interest in BTC futures is nothing? Seems like a pretty big deal in terms of legitimacy, if nothing else. It would be silly to assume institutional traders are all going to jump balls deep into actual BTC custody.
It's the difference between just another play on their legacy dashboard and delving deeper but I totally get why they'd stick with what they know if that old stager makes it available to them. Obviously in this case with such a huge portion of their funds it's a proper macho move.