Actually, JB weld sets harder than cement, it sets like steel. It's often used by mechanics to fix engine parts including cracked heads and blocks. Once cured it can be cut, milled, drilled, and tapped just like steel (well, close). I've never heard of thermal expansion causing it to crack.
Of course, gluing the resistors in with this stuff means there is no way they can be replaced, they're there for good! It makes a good thermal adhesive with the emphasis definatly on adhesive. If it was a component subject to failure, this would not be a viable option. The housing is big enough though, that if one did fail, I've got extra room to glue another one in.