Agree. Firmino already proved it in many matches that he has good emotional control. He rarely got cards, especially red cards. Even, I never saw him get red cards as far as I watched Liverpool matches previously. Honestly, I think Firmino is still much better in terms of winning mentality. Instead, the absence of Nunez may make Liverpool game better since they have better cooperation with an old player.
Firmino has proven his quality with Liverpool so far and I believe he is a player who deserves plenty of opportunities in Nunez's absence. Klopp knows Firmino is the right player for it, but nevertheless Klopp can determine what is needed in a game even without a centre-forward.
For now there is no certainty Firmino will fill Liverpool's starting line-up during Nenez's absence, but there is always the possibility that Firmono can keep Klopp's trust when he gets the opportunity by doing something good. I hope he plays against Manchester United, it will definitely motivate him to win.