It is not possible to stop the call to db after you run the report. The possible work around could be, in you dataset you can check the value of this parameter and execute stored procedures only if the parameter returns true, else you can execute simple select to return some static value. this will prevent your call to db and hidden function can present the report as if the report never executed.
Hope this helps !!
For those of you it did not work, can you may be give more information as to what you are trying to do, are you copying the code exactly, or making any changes? I am suprised because I tested everything before I included in the note.
always Happy, always Prasanna :-)