...That new guy is a jerk, but I honestly start to dislike MC, too. He is such a pushover. "Yes, of course I accept a SS-ranked quest, if it is troubling people, without any questions asked. Even though I want protect and reunite my LI with her family, I don't bother to ask the rest of my group." And everyone is praising him for being a pushover, that doesn't think about the consequences. That guy has no priorities set.
"I believe it is no good reason to fight over something like that." Is that guy kidding me? Of course it is no good reason. And that in itself is reason enough to not mention it. If he wants to answer the jerk just say something like, "If you are capable of defeating it and want to fight it, why is it still alive, Hero? Why didn't you put it down yesterday or the day before. I have to make preparations to subjugate that thing. If you are faster then us and beat me to it, so shall be it. I won't shed a tear about it."