Technically, no. (I've never understood how anyone got sequel from S-Q-L.)
And TLA is more correctly Three Letter Abbreviation. :-)
But like I said, I know there is no hard and fast rule. Acronym has had its meaning changed through popular use, and there isn't much to harp about there. It's as futile as pointing out that "begging the question" is used incorrectly 99% of the time.
For a style guide though, there's nothing wrong with insisting on a particular definition.
I've never understood how anyone got sequel from S-Q-L.
They didn't. They got SQL from SEQUEL (Structured English Query Language). After the name was changed from SEQUEL to SQL people just kept saying "sequel" since it's easier to say than "s-q-l".
Also is "TLA" an acronym, or do its initials just lie?