What is this ? 

it's a away to stop sonic screwdrivers and redstone affecting iron doors

why should this be in a mod ?

For RP reasons and Anti-greifing on  servers

How should it be implemented ?

maybe as an item that can add a deadlock that would make iron doors act like stone to the sonic screwdriver

Maybe timelocks could also be added. They would be set to a certain area radius (maybe 50-100 blocks in all directions. They would prevent TARDISes from landing in said timelocked location. This could be used on DMU to stop TARDISes from landing at spawn.

 Thats genius o-o

Yeah! I like the idea of the timelocks. Also with the deadlocks why not have it so the person who placed the deadlock for like their house their sonic(s) will be able to open the door as they're the owner.

To expand on Ron's idea, maybe a few people together could force a deadlock open, if they are not owned by the person who made the deadlock

 Maybe time locks could scale to an item you pay it like beacons, iron would be 50 blocks, emerald 100, obsidian 500, diamond 1000 and maybe things like johns black box (I think that's what it's called) that only john can use would have it's own imput so if area's expanded to over 1000 blocks it could still be protected

 with the power of barry mantilow ?

*mantilo and yeah maybe as an easter egg.