IANAL, but I believe that in most jurisdictions conspiracy requires two or more co-conspirators (i.e. the crime of conspiracy to commit a crime means two or more people agree or plan for a crime to be committed).

Attempting to commit a crime is also a crime in many jurisdictions, and only requires one person - maybe a prosecutor could convince a court that Derbasti was going to steal something, as demonstrated in a HN comment, but the plan was foiled.

Also, perhaps it is a threat - if other comments could be used to show that he/she was threatening the local supermarket unless they do something, perhaps charges for threatening could be filed.