Might Fred Ehrsam have some personal interest in Etherium, being a former Goldman Sachs trader (Etherium having been co-founded by Goldman Sachs alum Joseph Lubin)?
More likely Coinbase just started accepting ethereum trades because bitcoin is stalling and 2-3 other strong platforms(aka competitors) already offer it.
His basic point was related to bitcoin being not great "beyond store of value and speculation.", and how etherium is magically going to avoid that with killer apps.... sure...that is bubble speak for solving problems that don't actually exist.
I think you hit the nail on the head: he has a vested interest and ethereum presents a runway for coinbase.
IMO Bitcoin's problem, as depicted by this thread, is complexity, which ethereum adds more of instead of less. Make money work first, then create specialized verticals after.
