A motorcycle endorsement, for a Spyder, 3-wheeler, or 2 wheeler still does not mean a person has the experience, or the common sense to ride safely with consideration of the road conditions, etc. Taking a test in a parking lot or around a block or two means nothing. Once too many times, riding in a group and wanting/needing to keep up, will lead to an accident. And, I will state very strongly, NO ONE has any business doing twisties in a group without any experience. What seems like "slow" to some is extremely dangerous to others. I have been told so many times that I ride too slow that Jennifer and I will not ride in a group. Our safety is more important than bragging rights.
I am sorry about this incident, but it could have been avoided. Loss of a life affects people for a lifetime.