Yeah, part of the reason I didn't comment on it initially was because I wasn't sure of what to say. I think I have a better idea now.
Basically, OOC Planning really falls under the broader category of meta-gaming. Ideally, you're only using in-character information to plan character actions. I don't really want to try to determine what information your character would have, and what qualifies as in-character vs. out-of-character info. Maybe Jimmy noticed that Grant didn't have a gun, and would call him out for that reason. And to some extent it's good for you guys to talk about in-game stuff here, that's part of what this thread is for. As he said, he was defaulting to "polite" which isn't a bad idea given that we all don't know each other as well as a face-to-face group probably does.
So, all that said, I'm not going to enforce any sort of "no metagaming" stance. If it seems to me like it's getting out of hand at any point, I'll PM that player specifically and point it out. Otherwise, I'll just ask you guys to self-enforce. Try not to meta-game. Try to stick to what you think your character would know. But also don't feel like you can't talk about things here for fear of violating in-game knowledge. Just do your best to stick with what seems reasonable to you.
Is everybody okay with that?