You're right...PC doesn't have a significant amount of crystallinity, so it could be considered a glass (although that term can be confusing the the layperson). Some other amorphous polymers include PMMA (Plexiglass) and polystyrene. Polyethylene and PET are crystalline polymers. Although the crystallinity affects properties, the polymer chemistry and structure also play a big role. You can often make amorphous polymers crystalline and the other way around by tweaking the chemistry and/or processing.
However, the fact that it's amorphous isn't the main reason I would recomend against cooking with it.
If you have other questions along this line, I'd be glad to further discuss it off-line since this could stray off topic. My graduate degree was in Materials Science and I have been doing lots of permeability work (O2, CO2, and water vapor transmission) in the plastic industry, so I have enjoyed the level of detail that is included in the BPL articles and forum discussions.