In some situations maybe but not this team and not now. We just lost Reavo and we were pushed around prior to him coming here. There's nothing saying you couldn't have both types of response.
Maybe, but as you said: Reavo is gone. Who was going to do it? Trouba who is clearly playing through what appears to be a wrist injury? Outside of him or maybe Blais, who is also trying to work through a recovery from a significant injury last season, who else would you 1) risk an injury to fight a non-player like Lafferty? 2) wouldn't get immediately clowned by a guy who knows what they are doing in a fight?
Because it wouldn't be Lafferty fighting in that scenario. You are getting a Khaira, Domi, or Tinordi (if he didn't bust his face open prior) jumping in instead. Now you have a Kreider or Goodrow getting fed instead of just plastering that clearly shamelessly tanking team, getting the points, the goal differential, and keeping the streak going.
Edit: please don't say Harpur. Dude is big, but is absolute trash at fights, and even recently injured himself... fighting.