You're eligible. The website he's talking about is
here, and applies to the formal application date set by Monash Abroad, not the study plan thing. My advice in dealing with Monash bureaucracy is to bounce positive responses off people and make them deal with each other if they disagree. "Monash Abroad said it's okay, here's my application. Contact X if you need to." Also, try to avoid dealing with this Joe guy as much as you can from now.
I hate Monash bureaucracy and it's an absolute crock of bullshit. But if you can find one or two staff members who know what the fuck they're doing and will help you, latch onto them like your life depends on it and be damn nice and grateful about it. I went through a lot of shit because my exchange program was cancelled after I'd already arrived at my host university (2011 Tohoku Disaster in Japan).