I also can't tell you if it's genuine, but others here probably can.
However, from the purely commercial point of view ( since you say it's a dealer) you have possibly either found a complete ringer or a dealer who just shouldn't be in business given the internet access we have today and I doubt that, because 5 minuites on the internet will show up all sorts of examples for sale or sold. This link will show you what similar watches have fetched recently. https://www.collectorsquare.com/en/watches/rolex/submariner/ref-rolex-6538/lpi
There are many other examples, so Is it possible that any competent dealer wouldn't know that?
So, it shows a cse number of 383843. Have you checked that out first? That's where I'd start, although it's still no guarantee, as numbers can be fake, just like anything else.