Yup, and it's not just our bikes. I've got others with the same issue. It's a sickening crack when they let loose. You always wonder if the socket snapped, the wrench, or the plug. I only had one bike where the plug came out with the threads still attached (KTM). All the other times, it just took a real twist on things.
I think the last EH I had that happen with took a nice, crisp, sharp allen key and my jack handle over the end of it for leverage. Yeah, that was kind of overkill but, what are you going to do? It's gotta' come off, right? The allen key was bending but, it finally let go with the characteristic 'crack' sound.
Welcome to EH ownership and sorry about losing your friend.