No one is saying it’s an error, because it is more of an omission which could be viewed as an intentional withholding of pertinent information. Withholding of pertinent information can lead to a denial, just so you know. There’s a reason the DS260 has a section for other names (whether currently in use or used in the past)! Your background check will not be complete if the additional information that could have been used are not provided in advance. If you want to run into the possibility of being delayed for getting an approval after your interview, don’t disclose the name as recommended, wait until you show up for your interview and “explain” the omission to your CO. There’s no need for an email explaining anything, simply follow instructions and provide accurate information on your form which is the record both KCC and your embassy will go by.
I just don’t get why people ask for guidance, only for them to come up with one reason or the other as to why they will not do as advised and they will go with their previously decided option. I’m tired of this conversation. Don’t disclose the names on your DS260 form, do whatever you feel makes sense to you. I’m done and dusted with this!