Boiling may help but it's not so much the fungas as the toxin that causes the issue so if the toxin has seeped into the nut no amount of boiling is going to help with that I'm afraid.
I haven't heard about almonds or pecans causing problems but wouldn't rule it out, however, we give birds in hospital almonds occasionally. I'm not sure what it is about walnuts that the fungus seems to like so it grows readily. And the human grade ones are also contaminated I'm afraid. If you eat enough walnuts you'll probably stuff your liver up due to aflatoxicosis...
The problem with aflatoxins is that they accumulate so you (or your bird) could be eating contaminated nuts for a few months before the signs of toxicity start to show.
So yeah, I'd hate to commit and say yes, the walnuts will be fine if boiled. Its a hard one...
I'm heading back to NZ tomorrow (sigh...24 hours of travel ahead of me...groan!!) so I'll see what I can do about starting that nutrition article soon. I'll make sure I do a section on aflatoxins and include lots of links etc.