AR15 safety won't rotate to safe

[Currently]

Teaching a friend today on field stripping and cleaning his Bushmaster (made in Maine).

The safety selector doesn't look like any that I've seen before. It has what looks like a half inch long threaded stud that is less than 1/8 inch diameter, hollowed out with what looks like a stainless roll pin inserted into the hollow center.

In the fire position, this threaded stud is pointing straight up and it is located a third of the way from the lever side. It is not centered in the shaft.

I could not rotate the selector to safe position with the hammer cocked or further depressed with my thumb. It stops at the 45 degree position halfway between safe and fire. There is no debris or primers in the mechanism. (Been there, done that).

Before I take the trigger group out, I'd like to know what this is. I'm very familiar with trigger groups and how they work. The safety selector seems to have the standard shape and cam as a stock selector, in other words it is not the illegal type. To remove the selector, I'd have to remove that threaded stud in order to slide it out of the lower receiver.

Y'all have any idea what this is?

[Spots]

Can't say I've ever dealth with one like that. Maybe snap a few pics, that would be extremely helpful

[Currently]

Just found out it is a bushmaster competition trigger.

Thanks for help and advice received in chat!