What college is this?
I'm sorry to get in on this late (I don't think there has been a lot of Ontario input), but DO NOT contact the base hospital. You can read the directives as well as anyone and you know that this patient does not fit the FBAO cardiac arrest directive since there was no foreign body involved. Contacting the base hospital will be seen as trying to "go over the heads" of the college faculty ("above" them to a body that is completely independent of them). The base hospital will also not likely be receptive to this.
What is the consequence of having failed this scenario? Did you fail the semester or just lose some marks? If it is just lost marks, you should seriously consider how far you want to go with this since you've got at least one semester left with this program. And even after that, EMS people talk so much that you don't want to end up with a reputation before even getting on the road. I know it sucks needing to suck it up when you know you're right, but sometimes you need to play the game (take it from someone who has been there).
Have you seen the paperwork that says this is the reason you failed and the only reason you failed? Sometimes after scenarios students do not always hear all of the feedback that the instructor is giving them and they might focus in on just a certain area. Get the paperwork and see how they thought the entire scenario went.
The other consideration is that your college is sort of your base hospital right now. By this I mean that if they really want this type of arrest treated as FBAO and they taught you this then that is sort of what you've got to run with. I'm not trying to defend them, but the reality is that you're stuck with their rules until you graduate, get a job, and get certified by a base hospital. Even with the standard provincial directives there are still differences between the base hospitals even on things that seem clear on paper. For example, some base hospitals would not want epi 1:1000 administered to this patient if they went VSA before you could give it. As a keen student, you would reply by saying that the BLS Standards say we should though. That doesn't change the fact that some base hospitals have their medics not doing this even though it is clear on paper from the outside. If this type of scenario had been discussed before, you need to follow your base hospital, or in this case you need to follow what your college says.
Bottom line is that you're are correct and an arrest from anaphylaxis should be treated under the general arrest directive. The question is what you want to do about it. Your college should have a formal appeal process, which is what you will need to use if you want to formally challenge the mark. Timelines for this are very important and you may only have a week or less from receiving the grade to formally appeal it so act fact if you want to pursue that.