I agree with you that he's just talking and trying to adjust your expectations. There are averages, but no one can say exactly how things are going to go. Two years is not some magic line, I think he's just saying that dramatic changes in your mental powers are likely to occur before then.
I'm not a doctor, and my aneurysms didn't rupture; I just had them clipped a few months ago. BUT, two days after I came home from surgery, I had a huge series of seizures and so three more days in another hospital. The surgeon "can't really say" that the seizures had to do with the surgery, but I'm sure there's a relation.
After all that, I had some serious and very frightening problems with my short term memory (and balance, and even maybe speech, and I was just generally a wreck). So my primary doctor referred me to a special rehab program for people who've had various kinds of brain disasters: strokes, accidents, tumors, aneurysms, etc. In the course of that, I learned a lot about memory and brain function.
The main thing I picked up was that it's not hopeless. Your ability to heal may be strongest and quickest soon after the injury to the brain, but your brain builds new connections all the time and can learn to work around damaged areas. I think it's particularly likely that you could relearn something you used to know or get your ability to recall back to the level you used to have. The therapists stressed that it was important to get physical exercise -- something about that spurred neuron growth, and to take good care of yourself in terms of sleep and diet. Critically, they have research that shows learning new systems and processes-- things like math, languages, and musical instruments, were the best for building up the brain. And there are games and exercises that are supposed to help with short term memory, like Lumosity.com (and I know there are many others, I'm not shilling for them; that one just popped to mind). It's like anything-- the more you work at it, the better you get, although some people are always better at it than others.
Another factor is that it's hard to compare how one is now, in terms of mental capabilities, to how one (or one's family) thinks one was two years ago. Heck, it's been a few months for me, and while I feel 95% better and have stopped telling people the same things twice within three minutes (because I now remember having said them), I do wonder sometimes if my memory is really all the way back. I'm guessing your wife didn't do any testing that would prove how her memory was before, so you can't say for sure she's x% worse. Also, regular people have bad memory days, too-- as they age, when they're tired or stressed, or chronically for certain kinds of material, etc. I have an advanced degree and many academic accomplishments, but I have never been good at connecting names and faces, for example.
A big chunk of brain rehab class had to do with personal organization-- using a calendar, schedules, lists, a smartphone, reminders, making yourself notes and voice memos, repeating or rewriting critical information over and over so that you would start to remember it eventually. If your wife is back to work, then chances are she's doing all that pretty darn well.
One last thing: if she is taking any kind of brain medication, especially anti-seizure drugs, I can attest that being spacey and having difficulty remembering things can be a strong side effect of those.