The advice isn't bad, though Amy would've done better not to try to describe the inherently unknowable emotions of people she's never met and has only seen described in a few, brief words.

But yeah. LW's husband (probably) doesn't need to call his sons on their behavior - sounds like they're finally getting to a good place after years of struggles. LW's husband does need to step up and start taking all the emotional labor of these visits off his wife. How about, instead of her making dinner, they plan to order pizza when the stepsons arrive? Or, if he's so determined that they need to cook, he can do the cooking. Something fast, like pasta or burgers.