I always viewed Trashy as an inevitable agent of good. In other words, one that didn't know his destructive actions would ultimately bring down and destroy the cause he supports. It was the dark man's colossal mistake to have Trash on his side. He was the ultimate aspect of evil's irrational impatience. Flagg had to get those weapons ASAP at all costs. He could have waited for technicians to uncover books and manuals that showed how to arm the planes, fly, get the nuclear weapons, go to the white house, etc. Instead, he chose a short-cut. Short-cuts almost never work out.