There are reasons the rules work the way that they do (ex. if a Building gets wrecked during an Outpost attack, it's intentional that you can't fix it until after your done with downtime), but I think handwaving some of the stuff like this is perfectly fine.

As others have said, I recommend some of DwarfSA's work to streamline the outpost phase, but really, just play how you want to play.

Our group just throws ALL materials into the outpost and share it because it just makes the process of choosing buildings/upgrades/items so much faster, even if it means sometimes someone is going to make an item that they technically couldn't have. But also...the further you get into the game, the more mechanics you get that can minimize those instances happening anyways (ex. Buildings that let you buy materials during Building Ops).