First of all, it's not confirmed officially yet but its pretty much 'confirmed' you know
That being said, I think it's great. CoB will have a great opportunity on this tour, they'll have a blast, play crazy venue and be exposed to more fans. This is amazing really, not just the guys in the band, but their crew too, don't forget they are a big part of the band. Think about it. I think Slipknot will be headlining, then Machinehead then Bodom. The tiers are set by record sales usually, and Machinehead have sold far more albums to my knowledge, I mean they're waaaaay bigger here, everyone knows them. I'm not a big fan but hey, who cares.
If it upsets any of you, then guess what... DON'T GO! It's simple. Bodom will be back to headline probably in about a year so jsut wait until then. IMO Slipknot isn't even that bad of a band. I used to like them, and if they were playing here with Bodom I'd go see them.