As far as I remember, I haven't read Jason Aaron's work so I'm not going to comment on his abilities. Also, I'm an admirer of Alan Moore's work and I'll freely admit that's the only reason I cared about this column and it's the only reason why I'm responding.
I can't tell Jason Aaron how to feel about another writer. But I will say that his reasons for bashing Moore are a little muddled.
I know comics has always had and will always have its share of bitter old men. And usually those guys have every right to be bitter as the industry has a long track record of fucking over creators. But I've never had one of them actually blame me for their problems before. And I won't stand by and let Alan Moore do it either, no matter how amazing his beard might be.
Nowhere in the extended Moore quote that Aaron provides in his column did I read anything close to Moore blaming anyone for his problems. The topic never even comes up. He says that DC and Marvel don't know their asses from a hole in the ground - and considering he's talking about companies who come up with ideas like "Hey! Let's just throw the word 'DARK' in front of a bunch of superhero names," it seems like his criticisms, while harsh, are not unfair - but he doesn't blame anyone for his problems.
I'm not a comics news bug and I haven't read every Alan Moore interview out there, but I've gotten the sense in the last few years that Alan Moore is anything but bitter. He's doing his own thing and he's got the kind of clout where when he does his own thing, he doesn't need a Marvel or a DC behind him to get people to check it out. How long was he working on Lost Girls? How much did it cost when it came out, and how fast did people scramble over each other to get copies regardless? No, it doesn't seem like the possibility of working with Marvel or DC again would be desirable to him, and in this he's hardly alone. No, he doesn't sound like he's happy about DC doing everything they can to rape Watchmen. But, in the quote Aaron provides at least, he doesn't blame anyone from DC or Marvel for his problems. I mean, maybe there's a quote I don't know about, but you'd think Aaron might have provided it in his "Alan Moore is an asshole" column.
Seems to me that Jason Aaron is not angry about Alan Moore blaming him for his problems. Jason Aaron is mad at Alan Moore saying that Aaron and his colleagues suck at their jobs. That's a good thing to be mad about. I would be mad about it. I would hope, though, that I wouldn't manufacture bullshit to justify my own rant.