I do not think that it is totally marketing, he doesn't have to say it as long as he spends millions of dollars on marketing he could always get people to use his dex, I believe there is a bit of truth in it. This doesn't mean he is right, he could be very well wrong too and that means he is supporting something that will not be big, maybe dex will be forgotten and everything will go back to being cex in the end, but that doesn't mean we can argue what he believes in.
He could believe in whatever he wants that will be great in the future, maybe that is dex, maybe it is cex, maybe something we do not even have right now. CZ is not god in crypto world, he is a super rich dude but he is a CEO in the end and we shouldn't take what he says as the bible and believe him right away, he could be wrong as much as you and I can be.
Its not really part of my vocabulary on taking such steps just because some famous or known person do make out suggestions or recommendations towards his views on a certain thing.
There no indeed a God on crypto world that would able to know everything on what would be the possible movements yet i do always consider in shilling it out instead.
For marketing then yes, it do really plays a great role on one success but to know that there are several factors which are mainly needed to get some recognition.
In talks about DEX, on what features we do want? current Dex already had but still liquidity or volume still cant able to reach on what CEX achieved.