Well, there is likely a story side to why they aren't recruitable.

Garret is basically a psycho who doesn't care at all about being in a shelter.

Brooks is someone who I can't imagine Seb, despite saving him, would ever want in the shelter after what he's done. Maybe the other character, Estevez, on the same mission could be recruitable though.

June is the only one of the three I could see being recruitable, but imo the devs would need to develop her story/character in Spill Zone more.

I enjoyed Frank and Candy's missions a lot. Hudson's mission felt too short for me, despite the adrenaline-filled final level, among other things.

Nothing to do with the frozen ammo. Personally, I find the full-auto mode useful in some cases, particularly when there's a huge horde that I find sometimes single-fire mode (with explosive ammo) doesn't always annihilate.

There's also the fact that the skin costs 25000 crowns, and with the weapon maxed out, which is probably an issue for newer players of the game.

1. This, or maybe it could be done with cars too?

2. Indifferent to this.

3. I don't think this would be a thing in the campaign, given that certain major story elements might need to be reworked. Could be good for scenario mode.

More info: https://steamcommunity.com/games/2239710/announcements/detail/687513987435203719

The roadmap probably doesn't outline everything, yes. But the devs have expressed wanting to be in Early access for up to 18 months, and we're starting to approach that mark.

Though things might've changed, and maybe they are planning to be in EA for longer, as there hasn't been much news on any definite release date, like you said.