Yes, I think a stage manager should feel comfortable around fight work, but to be honest the time, the work and the cost to be certified may be a bit of over kill. It’s like . . . as a stage manager, we should know basic sewing skills, but I don’t need to be a draper.
BUT, if you have an interest, and you feel like you need more education in the area, go for it. (Chicks with swords . . . very sexy . . . and that’s coming from a middle age gay man . . . )