Nice setup, looks like it comes with a total of three forks. Some redundancies, CSS rims not really needed with disc brakes. But the Thorn fork has rim brakes. I think the flange support rings are installed on the hub.
The only thing I noticed on it that does not look right is that the eccentric has the thin wall side on the bottom, not top. Thus, the tightening screws are not pushing on the thick part of the eccentric.
My Nomad Mk II (590M with drop bars) has the S&S couplers and I have used it with a suspension fork when I was pretending that it was a mountain bike instead of a touring bike. But I have not used disc brakes on mine.
I am not familiar with different brands and models of suspension forks, so I do not know if that is a higher end one or not. The suspension fork I put on mine was a low end Rock Shox fork, so it is a good well built brand but not one of their more expensive models. Trying to find a new suspension fork now for a 26 inch wheel is probably impossible, I bought my suspension fork eleven years ago, only used it for two trips.
The only downside I see is no dynohub. But some people use solar panels instead. And if someone wanted one, it can be added.