It is very very odd. It would have had to been early in the outbreak when they met the Mallers. Durai having plans already was very odd. Who goes "Hey.. seems we got Zombies. Lets turn tankers into Bombs to blow up a nest just in case." or "Lets make Tankers into Bombs to break into people hideouts". That early into the game as well.

It could have been that he was just smart though. He sent Kulani as a spy to a tower, set up a system to monitor all the air waves, and was very good when he attacked the Tower. If Michael and Co had not used the Sweat then odds are they would have gotten though. Not just due to numbers. He has lookout posted to pick off any Zeds incoming. Fire Engines (Gathers and working as well. Means they had to find them and ensure they were working. Not just a quick pick up one day). It could have easily been that he knew he would need a Wall Buster. Got the fuel depot to ensure he had fuel and be able to make what may be the powerful weapon left in the world (Outside of the Nukes, but that was a thing unto itself) just because he was a planner.

I have always said that Durai was a lot smarter than we knew. Scratch just let him out and got stuff done, but my gut says that he was a smart leader. Pulled his resources and made something out of nothing.