What exactly is not safe? That they wake up agitated and possibly violent? Isn't handling violent people a big part of a police officer's job? And exactly how dangerous would they be if they start out from a semi-conscious state where the officers have the advantage of being prepared for any potential outburst? I mean they could even restrain the person prior to administering the drug.
Police are sometimes involved in dangerous situations as part of their job, but that does not mean we should create more dangerous situations for them.
It is sometimes difficult for even trained individuals to tell the difference between someone having an opioid overdose and another type of overdose, or something else altogether. Where there is a known opioid overdose situation, paramedics should be dispatched to the site simultaneously with the police. Where the situation is less clear, there is no need to expose a lone police officer to a potentially dangerous situation that might, if all the circumstances line up correctly, merely allow the addict to "live" until their next overdose, potentially committing crimes to feed their habit.