Well, I think show organizers couldn't find another World Champion level male skater. First, they tried to invite Evan but failed (He came to the Super Class show managed by IMG). Probably, they tried hard to find that level, but failed, I guess. At least, Adam is a reghning Jr. World Champion.
BTW, Shae-Lynn Bourne was 2003 World Champion.
There must be other reasons than that because Butle said he was considering participating in both shows. Maybe some scheduling conflict. I wouldn't say Rippon is out of scene given his popularity in Korea.