They should've wondered why Negans people need all this food and would increase their demands. Wisdom would say you don't destroy your food supply, so clearly they need to feed a lot of people. This is all a bad idea and I give Hardwick credit for sorta saying "this seems like a dumb move". He's rarely critical but was on this one.
It's definitely a bad idea, but it does establish one major difference that will help the show chart a different course from the comics.
One of the first thing that happens after we're introduced to Lucille and its first use, is that Maggie basically slugs Rick and blames him for the death.
In the show however, it was Maggie that negotiated with Gregory & the Hilltop community what the Alexandria crew will do in order to get food and supplies, so if they keep with killing the same character that they did in the comics, Maggie will only have herself to blame, not Rick - especially since Rick's plan was going great until she got her ass caught.
So yeah - definitely lots of dumb moves on our main crew's part in this episode...
I'm pretty sure those pictures Glenn found were Lucile's handiwork.
They most definitely were. My thinking is that this does have the potential to be a sign that a different character or perhaps none of them at all will be having a one-on-one date with Lucille. Fingers crossed...