You're right... When I read that I read increased defence and special defence stats. Probably 'cause that's what I wanted/expected to read. Well, I guess mega Sableye is just going to be a fantastic physical wall. High defence, will-o-wisp, recover, immunity to status, lack of common powerful physical weaknesses. It won't be the mixed wall that people were expecting though. With the new role it'll play though, it should see some use over its ordinary form in teams that want a good physical wall.
Dunno why they gave it increased special attack, it starts at 65. They can give it 40 of it's 100 points and it'll only be good. Still, I guess shadow ball/dark pulse will give it something to do when it isn't burning things or getting it's health back.
On the plus side, magic bounce drops Sableye's reliance on priority taunt as it now can't be taunted.