Joseph,
it depends on thne situation. I agree with you that no kiruv person would outright tell someone to drive on shabbos, and I agree also that if asked they would tell the person that its better to stay home. However if the person doesn’t ask specifically about this then I’d agree with SJSin NYC that if the person would find it hard to break from the conservative congretation he’s belonged to for years then it may be better to take it slow and not tell them right away to stop driving there. Maybe first get them comfortable keeping shabbos on friday night, then maybe dropping the saturday afternoon trip to the mall or the movies, and only then dropping the drive to the conservative temple on shabbos morning.