Thank you for your 'Ninja' skills!
She is amazing, isn't she? Thank goodness she's always here to offer her valuable advice.
With that being said, I certainly wouldn't complain about an inflated shipping charge of $24.09. As a long-term buyer, you saw the shipping costs prior to placing your bid and by placing said bid, agreed to those charges.
I'm a long-time buyer/seller myself and I've received a lot of packages that had SC on them that didn't meet that magical $750 threshold for SC. (I'd say close to 50% of my packages) SC also wasn't mentioned in the listings and they were mostly relatively new sellers. In my opinion, you really can't fault a new seller for wanting to protect themselves.
As for FB, I certainly wouldn't fault a seller for shipping an item to me just because they chose to use SC. I've checked eBay's policies and found nothing stating that a shipper had to alert a buyer that they are using SC. Be forewarned that if you chose to give positive FB with a negative comment regarding shipping (soft positive) you will get a ding on your account as this is not allowed and against eBay policy. (One of the responses suggested doing this)
On a side note, I only use SC for purchases that are $750+ adhering to eBay/PP policy however; I have noticed within the past year that nearly all of the packages that I insure only (No SC) are sent out aren't being delivered without SC. I called the USPS as well as Consumer Affairs to inquire about this and was told this was due to the USPS having to pay out too many claims they're being told to get a signature on file for anything insured that's over $200. If you haven't experienced this yet, you will. I do realize that you're referring to FedEx but you may find this happening frequently in the future with USPS packages as well in regard to SC since you're a frequent shopper.
I hope this information helps. While I understand SC may be a hassle for some, the topic seems so trivial to me at the moment with having a sick elderly mother who I'm losing, not to mention being awake the entire night at the emergency vet with my 5 year old dog who tore her ACL and from what I'm told has an aggressive form of arthritis in her hips, knees and back that I'll also be losing soon.
If you still have parents, a spouse, significant other, children, pets, etc. that you love and are healthy, go home and give them a hug. There are more pressing issues out there than worrying about a newbie seller protecting themselves by paying for SC.
Good luck.