I can assert that because I have what is known as RI (real intelligence).
Sentience is defined extremely well, and explicitly; check out both definitions:
https://www.merriam-webster.com/dictionary/sentience
Go ahead and click on through to the root word and check out every definition of that word.
https://www.merriam-webster.com/dictionary/sentient
You could make such assertions yourself if you were to stop cognitive offloading and exercise your brain.