I think you still have a chance of winning - a good chance, with a good lead already - if you keep going. Or, if Henry goes missing again, Mas might just replace him with Than... hint hint.
Going to the Death Match deliberately is an unsure move. Even if it is Sam, something could awry. You could lose. Or you could be doing really well until you get the flu, make passive aggressive comments about wanting to do match 4 that next day that no one bites at, puke your guts out around round 3, and just decide "fuck it" mid challenge (heh... sorry, love you Mas and Mets!).
I'd still *try* to win... at least for this round and the next, at least keep yourself in the playing. If come round 3 your assistant is still missing, and you really want to go... then do it. It's up to you, though. If you want to go to the Death Match - you're the one still in the game, it's entirely your decision, and I'll gladly do whatever you ask. But I'd *suggest* rethinking it.