"From what I can make out the fastener screw looks to be both TORX and possibly a hexagon on the outside."

Looks that way to me too. I checked the original images -- before they were sized for the internet -- and they are no clearer. Just a poorly focused photo.

However, my memory would have jumped on a special, nonstandard fastener, and it did not. Having been through many cars of that general time frame, I've concluded Volvo began its switchover from Phillips to Torx with the 1990 model year. So I believe it is just a standard M4 Torx bolt just like all the others, despite the photo looking like I stuck a nut under its head on top of the ring lugs. It has me curious enough to tear off the cover on the steering column to explain this appearance, but alas, all I have at home is cars 1989 model year and earlier. Perhaps one of my kids will bring one of their cars for me to look at.
--
Art Benstein near Baltimore

You have to stay in shape. My grandmother started walking five miles a day when she was 60. She's 97 today and we have no idea where she is.