You should always bleed the brakes, for two reasons:
Like any fluid, the hydraulic fluid in the brake lines will deteriorate over time. Bleeding the brakes regularly helps to flush this fluid, so you don't end up depending on crappy, worn out fluid to save your life.
The system is also not designed to be pushed backwards and held for long periods of time, like in the case of putting in some brand new thick pads that push the pistons back into the calipers much further then with the old thin pads.
Tell them to bleed the brakes, or take it to another shop that will.
Do not take shortcuts with the critical systems on your truck.