I think we could argue at cross purposes for ever. It seems a pretty artificial distinction to me. High explosive is a chemical as is Uranium235. It is bit of an argument over semantics in reality, rather like barrel bombs. A bomb is a bomb, is a bomb.
The actual wording below is far from precise.
https://www.opcw.org/chemical-weapons-convention/articles/article-ii-definitions-and-criteria/

http://en.farsnews.com/newstext.aspx?nn=13940721001520
Will the OPCW be in any rush to check out the above?