I can see the other players on your squad probably typing up the same post from their perspective right now LOL. But don't get it twisted - player 3 is a certified asshole.
If I join a farm and find the majority of the squad using a method other than the one I think is the best, I'll usually entertain them for the minimum commitment and dip afterwards. I would feel like I'm trolling if I ran off to do my own thing, even if it's "meta." This is just my opinion.
You shouldn't worry about the report, but let's say even in the worst scenario you get punished for it (not sure how, but just assuming it's possible.) Email DE support and explain what went down. They'll do the right thing. Don't feel bad for what you did! You used the report system as intended.
Exact same situation happened to someone I know. They spent like 30 minutes in the mission, then realized what the bounty requirement was. Tried kiting some enemies outside, but they wouldn't spawn. So unlucky.
Also, was peeved when being in Jade's AC-130 didn't count towards killing enemies from high ground. Can't get much higher than that.