I understand the idea of pinning a fingerboard during construction, but a roll pin? And a big one at that. It gets better, that's a Martin bass.
I've got a number of martin fingerboards and necks, circa 2005, seconds, and they are all drilled for roll pins and the necks have the pins in them. They look just like the one shown in the ad.
Interesting. They can't possibly be driving the roll pin into wood and have it perform it's intended function. And it looks way bigger than what I've seen other manufacturers use. But we are talking Martin...
I've also have some tops from that same era with holes that match holes in the fingerboard extension. I speculate it is an alignment system for glueup of the neck, fingerboard and body. The necks are tenon not dovetail. I've used a few on builds and left the pins in. Worked OK for me.
Thing is, a roll pin is typically used in an application where it can be driven into a hole that is smaller than the nominal OD of the pin. Usually in some sort of metal. It then compresses a bit and stays put. There is no way that this scenario could be effected in a piece of wood. A simple small nail is sufficient to keep the finger board from squirming under clamping. Sorry, my mechanical engineering background jumped up and said "Huh?"
I'm just describing what I have experienced with these parts. I don't have your background to question the system. Perhaps ask John Hall or John Arnold who have more background in Martin parts, repair and kits, or check UMGF.
I'm not saying it won't work, obviously it does. It's just overkill.