Here's an interesting article. I dont know if she's right or wrong I havent handfed in 14 years and didnt have this problem BUT it illustrates how complicated it can be. Sounds like she's trying to say it's ok to sell babies to inexperienced people I dont know. I only skimmed it.
But it may make you feel better. Explaining how they regress during weaning. And if they are starving they actually wont eat sometimes. Very complicated stuff. This is why they want to unload the birds in the last stages since it's more tricky I guess.
http://www.cagenbird.com/weaning.htm