Why isn’t klipspringer going to attend the funeral?

Klipsinger doesn't want to be involved or associated with Gatsby at this point. In order to escape going to the funeral, he comes up with a story about visitning friends, who expect him to join them on a picnic.

“Well, the fact is — the truth of the matter is that I’m staying with some people up here in Greenwich, and they rather expect me to be with them to-morrow. In fact, there’s a sort of picnic or something. Of course I’ll do my very best to get away.”