I would just like to say something about the players and their characters. However, I'm not going to discuss the issue between Lawrence and the others. It's related though.
Why do you guys participate in a self-running RP if you can't accept your characters dying?
If one character can't die, it basically;
1/ Destroys any point in engaging them in combat. (Unless it's sparring between two players for fun or skirmishes with unnamed npcs, which, I hope from the bottom of my heart, won't constitute the essential part of the fights)
2/ Ruins any tension when dangerous situations happen.
3/ Makes the whole RP boring, because it's close to godmodding. Yes, not dying is basically cheating.
I understand that you brought characters you created and/or that you like in. I understand that you don't want them to get stomped. I understand, trust me. And that's one of the reason why I did come up with a bunch of OC characters. However, even if I went with characters already existing, I wouldn't mind them dying, even in such an unexpected event which justified three pages worth of argument.
Why? Because player characters dying are tools to move the story forward. Enmity, anger, grudge, affliction, regrets, sadness, doubt, etc... are as much elements to use in order to develop your other characters and even generate mini-story arcs. How they react to it, how they adapt to the situation, how they move on, how they decide that it's time for payback, etc... Drama is a good thing. Don't reject it stubbornly for your own satisfaction to keep more PCs around. It can benefit greatly not only for you, but also for others.
If my characters die, I'll bring others. It's not really a problem to me. If your characters die, what will you do? Stop RPing? Don't be like that. We're there to have a good time. If they die, they die. Just part of the game. Nothing much happens outside the RP. Shrug it off and think about how you can exploit the situation to make the whole thing more interesting for everyone.
Finally, asking the GM to choose for you what's going to happen is only a temporary solution. Settle the problem between yourself like adults. If the GM decides something that doesn't go your way, you'll get mad. (Perhaps enough to drop the RP)
a/ If Elf decides Lawrence fails at reaching Connor with his shot, Arch will argue how impossible that it is at that range. (And also adding the fact that he could always shoot again anyway)
b/ If Elf decides that Sakura/Connor doesn't have a way to stop/avoid the shot, Lantz loses a character.
c/ If Elf decides to intervene in another way, it will only be for this time. A similar situation will eventually arise again. And even in the case we wait for the GM to choose once again, it will lock any confrontation in the future because nobody will want this or that character dead.
I really don't want to argue over details about who's in right or not, who's supposed to get the upper hand in the situation right now, etc... Simply, we shouldn't have to rely on Elf for this. Not siding with anyone, but if we want this to work out, people will have to make compromises.
Just my two cents, anyway.