Cold pack contents can be used to make home made Tannerite if mixed with powdered aluminum. Hardly a bomb. Can be bought and sold legally by mail
Cold pack contents (assuming that the cold pack uses ammonium nitrate) can also be used to make ANFO, the
high explosive blasting agent that McVeigh used to blow up the federal building. Of course, in a farm state like Nebraska with large quantities of fertilizer around, ice packs seem like an expensive way to get ammonium nitrate if you are a wannabe terrorist looking for a stable ingredient for making "bad guy" explosive devices, rather than a firearm hobbyist looking to brew your own exploding targets/stump removal devices.
But yeah, ammonium nitrate is what I think of when I read "As to Lear’s alleged intentions with making bombs, Lt. Paul Vrbka said that is unclear and that aspect remains under investigation. 'But these materials are very indicative with assembling bombs, we just don’t know what they were intended for, at this point.'"
The other possibility that springs to mind is that this guy had some kind of crazy looking project going with protruding wires or something that just looked "bomb-like."
I'm a libertarian, so I don't like laws prohibiting the possession of substances, whether they be the psychoactive kind or the violently reactive kind. But with that said, I don't have much respect for a guy who is smoking meth and building bombs with kids in the house. If you want to endanger yourself, fine, but don't be reckless with your kid's life.