I'm sorry mate you are a terrible first aider and you should reconsider your approach before someone dies on your watch. As an EMT, loss of consciousness is absolutely something that warrants clinical assessment by a healthcare professional.

As a first aider you should understand the chain of survival, one of which is "early access to advanced care". Delaying calling the ambulance completely violated that training. You should understand that the protocol DRSABCD has "send for help" after any response less than "alert" is identified. Your anecdote already shows you cannot follow the protocol and are not acting within your training. It also doesn't say "go back and cancel the ambulance if they regain consciousness". The training is simply "put them in the recovery position" which implies "and wait for ambulance to arrive".

The reason it is taught that way is, you are not a doctor qualified to diagnose whether someone's complex condition is an emergency or not. The absolutely worse thing you can do is make the wrong choice and delay necessary care. The best case is the paramedics come, assesses the patient, and decided they don't need to go to hospital and they go on their merry way (at no cost to the patient). So for you, you always make the worst case scenario.

It's not your responsibility as a first aider to consider the strain on the ambulance or the financial outcome to the patient. Your duty of care is to the medical outcome of your patient, nothing else.