To be fair to the argument, there are ways to do RT light as well.My opinion? Cerny is as far from a PR guru as you can find. He really is a matter of fact kind of guy, as demonstrated at the PS4 reveal where he simply explained what the system had inside, showed off some rather underwhelming demos (compared to what we actually got from some games) and off he went. As opposed to Sony’s older attitudes, which need no further mention.
I’d be very surprised if Wired explicitly asked him whether PS5 supports RT, and at the same time I don’t think Cerny would have mentioned the feature - and with this much effort trying to explain it - if he thinks he can just get away with, ultimately, it not being used in reality.
It follows that he would expect RT being accelerated somehow in the platform and that devs will be using it in some shape or form.
There's fair argument on whether or not there is hardware fixed function support or without. I generally think there will be, because I'm not sure yet if we're at the point in time in which we can go without it just yet.
I have a 'strong' hunch that AMD is working on an accelerated solution.