The list at the link you provide was first put online here(at least it is the earliest that I can find)-
Most of the BBQ forums and many websites use a copy of the original list, sometimes attributed to someone named Pat Lehnherr-
Glad to see that someone has backed it up on another site.
That said, yes, many people use avocado with great success, one poster on another site
reported that avocado reminded him of a mild hickory.