I have seen some heat treating instructions that mention oil quenching, but my point is that temperature control for A2 is precise and time consuming. You are supposed to heat it to between 1750 and 1800F, but raising it no more than 400F per hour, so a four to five hour heat. Then quench it in still air (or oil) to 150F and immediately temper to between 300 and 900F (depending on desired Rockwell hardness), soaking it for four hours.
Somehow I doubt that this guy did that. It might be ok, but it's a gamble.