Just a couple of thoughts here, sorry for interrupting the conversation.
First, in defense of the dealership, please excuse the comments that may have been made. I have heard quite a few of them, including " it's a car, not a submarine". Rest assured, that is not the direction Volvo as a company takes. Communication between customer and service personnel gets a little quirky at times.
Second, as this problem seems to be isolated to the type of car wash that you use, I would suggest that you gather as much data as to pressures, the type of spray pattern used, and then do a bit of research on your own. Plenty of information out there.
Next, as to the design of a sunroof. Most modern retractable roof openings have a gutter or drip rail system in place, with drains attached to an opening to the exterior of the car. The sealing systems always have the possibility of water egress, and are designed with that in mind. The systems are tested in a variety of ways that include multiple levels of water volume and wind. Of course, they are wind tunnel tested to speeds that are above what your vehicle is capable of. It is a piece of glass that is movable, therefore it needs to have a bit of give to withstand all of variable stress that is put on it in normal usage. So some deflection or distortion under direct high pressure force is understandable. If not, you would end up with a bunch of little chunks of sunroof in your lap when you hit that wash!
Finally, I would approach the dealer with as much information as to the issue as possible. An adversarial stance never helps either side. Many dealerships will have a shop foreman or technician that may be available for you to speak to. Many times its helpful to go right to the person that is going to assess the problem, so no information is lost or misunderstood. Ask your dealership if that is an option.
I have been on both sides of this type of problem, from owning a vehicle with a leakage problem to fixing water leaks in a dealer environment. In a better world, you and a technician would sit down to a coffee for an hour or so, and review design, functionality and a direction forward related to your issue. Until then, focus on presenting the issue in a way that gets results, trust me it helps!
Now, back to your conversation here, sorry for butting in.......