I would agree that, if your buddy is in a near-panic, they will probably go for your primary rather than your backup 2nd stage. It's way easier for them to find. They have to be calm to politely signal for your air and find the alternate. So it definitely behooves you to be ready to find your own backup octo quickly.
!
Lots of people say that, but I and a lot of others dispute that. In the only case I have ever been near, the OOA diver simply grabbed her buddy's alternate. When the same sort of thing was being said on a SB thread a few years ago, I polled most of the instructors at the shop, and everyone of them said that was what happened in every case they knew of. None had ever heard of a diver grabbing the primary. They had apparently gone for the regulator they had been trained to go for. Sometimes they even signaled first.
Maniago, Without some kind of notice, an OOA diver is going to find me pushing them away if they reach for my regs. Period. I am going to ensure my safety and not allow a panicked diver to wrap me up. Once I am clear of them the very next thing I am going to do it stuff my regulator into their face and grab my backup from (around neck, airsource, etc). To me, it's not the other persons choice what they get. I'm protecting myself first and by doing so, protecting my ability to help rescue them.
This is just about exactly the last thing I tell my students to do. You do not want to start a fight under water with an OOA diver. It is an almost certain way to cause at least one death, and possibly two. Do you really think that an OOA diver is going to passively back off when you push him or her away? Are you such a gorilla that you will easily overpower that diver, get him or her to calm down, and then give him or her the regulator? Or will that diver go at you with the superhuman strength of someone possessed by panic?
I tell my students that no matter what you practice, with a conventional octo setup, the OOA diver determines what happens:
1. If the diver reaches for your octo, which I think is most likely, get out of the way. If you try to hand it off, you will inevitably bump into each other and cause problems. (This is how BSAC teaches OOA, and for that reason.)
2. If the diver signals and waits, hand the diver your octo before panic ensues.
3. If the diver reaches for your primary, open your mouth and let it go. This is not the time for a fight. Take your octo yourself and sort things out once the diver is calm and in control.