I think it's just a difference in the way the two companies do "public".

Because Facebook hates Google, you're far less likely to see public posts turn up in Google results.

Google, on the other hand, created their network for the sole purpose of bolstering their search results. This leads to a much more adversarial relationship with the service, where you have to constantly fight to keep yourself out of the spotlight.

Note that she didn't address Facebook, at all. She confined her comments to Google+.

So, while the FB comparisons may be appropriate to conversation here, they do not -- in my view -- imply a weakness in her argument. She left FB outside the scope of what she was saying and whom she was addressing.

P.S. Upon rereading, I do note this bit:

particularly when there are other social networking alternatives with simpler privacy settings.

which perhaps weakens my original argument in this comment somewhat.