maybe for safety reasons for a guy like Chael
The reason that Brazilians have such high win ratios in Brazil is because they're facing overmatched opponents. Now if you get sent to brazil to fight a brazilian it's probably for one of two reasons:
1. You're not that good, and they're using you to hype up a good brazilian prospect (in which case you might as well take the fight, since you're not that good and it's not like you'll find a much more favorable match up anywhere else. That or you're being signed for the first time in Brazil, so you should be jumping on any opportunity to fight in the UFC).
2. You are a good fighter being used as litmus paper for a legit Brazilian (IE: Bader, Shields), in which case you should sign the fight because you're good and should have no doubt in your ability.
Beware of robberies though, they do happen