Others have noticed the same thing I have: The misuse of “tenant” for “tenet” seems to be increasing.
A TENET is a foundational belief, a cornerstone of an ideology. (That’s my definition from my own head. You want something better, look it up in your preferred dictionary.)
A TENANT is someone or something (it can be a corporation, sure) that rents space from someone else. If you’re a renter, you’re a tenant.
Beliefs certainly occupy one’s mind, but that doesn’t make them tenants. They don’t pay rent.
Side note: The actor who portrayed the Tenth Doctor spells his surname with two N’s. Tennant. So does the Pet Shop Boy Neil.