I have read about several persons putting safety pins on a keyring for EDC. I would like to know how you keep them from opening and poking through a pant pocket into your leg or something worse. Anyone out there with help?

You could try diaper pins, they stay shut pretty good. If there still is such a thing! Everyone uses disposable diapers on there little ones nowadays!
I keep a few safety pins in my wallet, they get trashed after some time. Useful when you bust that zipper!

I keep safety pins on my keyring. Mostly the problem you are concerned about doesn't happen. It's kinda the point of safety pins to be safe.

I keep them on two small split rings, mainly to make a tight bundle. I don't know if that makes a difference.

I had them on my keyring and they opened up on me. Need to fix them.

Wrap a sliver of duct tape around the sticking end, after closing it on your keyring. Two or three loops around will keep it secure until you want it.