My local shop has you sign before they sell mechanical mods or rebuildables. If you buy a rebuildable there they will do the first build for you, at a resistance they feel safe with, nothing below .6. They will also be happy to look at a build you made, they looked at my first attempt, laughed a little, and said it would not blow my face off at .9 ohms.
The waver is a CYA for insurance and it does point out some of the potential problems building. You only have to sign it once.
I also don't think it would hold up in court.