The wastes are a dangerous place, but there is no way that Dean will let his father's murderer, or his pack, mate with him or Sam.
Better to be lost in the wastes.
Then, when he least expects it, Dean ends up forming a pack of his own.
It was dangerous for two omegas to be out in the wastes by themselves.
Dean knew this when he'd run away with Sam from the camp they had been in, escaping the pack that had captured them. He'd been mentally keeping track of the days and he knew that their heat would be on them soon. Knew that there was no way he'd allow those filthy alphas to mate with him and his brother.