As far as I know, from what we've seen, Malcom doesn't have an actual final 3 "deal" with Reynold and Eddie. With that, why he himself didn't go straight to Eric and Sheri and say something like "Look, you both have to know you're on the bottom of your alliance. Switch with us, and we are the final three." Do a pinky swear, make a blood oath, whatever it takes, make them believe you. Sweep down to the final 5. Whichever of Reynold or Eddie doesn't win immunity at 5 goes (Reynold if it's neither of them), and then the 3 of them play against the one that's left in the final 4.
I think I'd prefer Erik and Brenda if I was him, because then he can make the argument that he wants to take fellow "favorites" with him to the final three, because if he takes the two "fans" he might lose to a bitter jury. If it's three "favorites" they can't vote against all of them. But I don't think he has the guile to pull Brenda at this point.