You've made it clear how you feel about OAO, why not just leave it at that? lots of assumptions though in your post.
You said you dont care about OA and you dont want to work there, thats great... means people who do actually want to work there get a job. Why not let them make their own mind up though instead of vocalising your negativity.
...plus it's a foot in the door. A chance to do the assessments, medicals and get the necessary competency/training - which IF things don't work out down the line, gives you a much better chance at getting in with another operator as you have the necessary experience and qualifications to take up another position quicker than someone starting from scratch.
If the role gives you PTS and competency to work on 800s, then you've got great transferrable skills for all the other operators using these trains.
Edit: I see you cancelled; is it too late to change your mind and carry on?
I was on the 1400 Assessment.