Guess this is where I step-in and become the only one on your boyfriends side
My first snake was and ATB
There is NO REASON why he should not get one. You're on a Cornsnake forum, so, of course, people here are going to say no way.
I, on the other hand, suggest he go for it!
The important part for both of you to understand is that ATBs are NOT corns. Not in any way shape or form. Their care is different, their attitudes are obviously different, everything is different.
No colubrid or terrestrial boa that are normal "starters" are going to be able to prepare him to keep an Amazon.
I suggest he read up on them - check out corallus.com and urbanjungle.com for starters. Both are excellent resources, and all of Danny Mandez's info on UrbanJungle is spot on.
It's essential he learns that these are NOT snakes to be handled. Sure, there are a few out there that are "tame" but they are exceptions to the rules. You can usually get away with handling for a short time, but the ATB will likely get the best of you for the most part. I have a couple that I can handle for a few minutes (make sure sheds are OK and no mites) but for the most part they are hands-off, display animals.
Thats Caution
my first snake
I had two or three more Amazons before I ever had a cornsnake - and even that was a rescue...