The sources listed above are pretty clear.
- Source #1: "Do not give anyone online your real last name, phone numbers at home or school, your parents’ workplaces, or the name or location of your school or home address unless you have your parents’ permission first. Never give your password to anyone but a parent or other adult in your family."
- Source #2: "Children’s full names with a photo of the child should not appear in this site. If you find a child’s full name with a photo of the child is accidentally placed on a page in this site, please report the error to the content owner, listed at the bottom of the page, or to the Director, Marketing & Communications".
- Scource #1: As with a Scouting activity, safety and Youth Protection should be a key focus. Staying true to the commitment of the BSA to be an advocate for youth and to keep children and their privacy safe, both online and off, should always be at the forefront of any considerations where social media usage is concerned.
EDIT: The talent release form is the only form where you have the option to disclose your full name.
Source #1 (A): This language applies to Scouts and should be used as part of Cyber Chip. It is not a prohibition against units using Scout's last names - it is a suggestion to the Scouts that scouts shouldn't use their last names, post anything about school, etc. In fact, the introduction to that entire section states this: Any Scout units that plan to use social media should share the following Internet safety guidelines with Scouts, parents, and leaders, and all Scouts should abide by the following Internet safety guidelines and personal protection rules. That's a section of advice for Scouts and parents - and it's not even a requirement that the unit must follow - look for words like should - that means it's a suggestion, not a requirement.
Source #2: That's the rules for that site, and only that site. It's a good idea for units to follow - but it's not a requirement that units need follow for their own websites.
Source 1(B): Again - it's a suggestion - they use the word Should again.
Understand that I am not disagreeing that its a really good idea for Scout units not to post Scout's last names - Just let's not say that the BSA has created rules and requirements that Units must follow when they haven't.