If the family wants him there he has an obligation to attend.If,by chance,the family wants a private,low keyed funeral then yes,it could be argued that he shouldn't attend.But it's hard for me to imagine hi family wanting,or hoping,Shatner not to attend.
Alrighty, let's create a controversy based on the big "IF"...........sheesh
Given the fast turn around on Jewish funerals the family understands not everybody can be there. I’m sure they’d like him to attend but 2 days is a tough turn around. He’ll get there when he can, they’ll commiserate. Adults understand that there are things you can’t attend.