I said this before - every glass installation I have ever seen (since WW2) with "on the seal" moldings is done this way. I'm an engineer and it seems perfectly logical to me. It locks the molding into the rubber securely, it stabilizes the rubber seal, it saves production time at assembly and in the field when service is needed.

It really is quite simple and easy to remove and install the assembly, and in fact, to correct the problem you started out with, it is the ONLY way you can get to the problem area to remove ALL the rust and to weld in a small patch of steel. Once the rust appears on the outside it is almost guaranteed that you have a hole near the flange.

I'm done here. All this debate has taken more time than it takes to do the job.