So I just got off the phone with Citicard Benefits Dept, told her what Costco said about the 2 year extension no longer being offered. She told me they are still offering this benefit, that the info on their website is still valid, and that they have no plans to discontinue this benefit. She is sending me paper documentation per my request.
I called Costco to let them know I was misinformed at the store, and told them what Citicard said. The Costco employee seemed to recall an email their management received indicating that the Citicard 2-yr warranty extension benefit was ending at some point (she wasn't sure exactly), and therefore they stopped actively promoting it in their stores and on their website. She said she would bring this issue to the attention of management at their store.
Thank you to
@doboy for providing the Citicard site link.