Health, I have mentioned this several times, the first responders usually are on scene with the patient before the ambulance arrives to assess and treat. To where should they take the patient, to the street?
In a typical scenario, the first responders arrive on scene and if not already dispatched would request ALS. The ALS would usually be on scene pretty quickly and initiate treatment. All of this prior to the ambulance arriving on scene. If it happens so that the ambulance is on scene before The ALS providers, the EMts would initiate transport and meet up with the ALS in route.
Besides, not sure why there would be an issue of requesting ALS as this is a unstable patient. Requesting ALS does not waste time and can make a difference in patient outcome.