Yes, as far as I know...they CAN call it bourbon even though it's charcoal filtered BUT they can not call it TN whiskey because it's made in KY (Heaven Hill). The rules for bourbon in general: 51% corn, made anywhere in the USA, aged in new charred oak barrels, distilled to no more than 80% ABV, into the barrel at no more than 62.5% ABV, bottled at 40% or more ABV.
If it has been aged for a minimum of two years, and has no added coloring, flavoring, or other spirits, & meets the above criteria, it can be called "Straight Bourbon".
The Lincoln County process refers to whiskey being charcoal filtered in that specific process developed in Lincoln County....but not all TN whiskey is charcoal filtered. TN Whiskey is "Straight Bourbon" made in TN. TN whiskey is a legal definition - must be made in TN. Many TN whiskey makers just don't use the word "bourbon" on their label but legally they can, if they meet the above bourbon criteria..... JDaniels, Dickel use the TN whiskey name to set themselves apart from KY bourbon.
FYI: Benjamin Prichard's is a TN Whiskey (bourbon) that does NOT charcoal filter.
Don't become a fanboy.....always question, stay skeptical & follow the money.