Here's my main concern:
In a tank that doesn't have a high bio-load, probably won't have a "super" high bacteria count.
I agree that a bta needs an established and stable tank. I would be concerned amount the amount of bacteria vs. the load you would be adding. If you just add the anemone and the clowns, that is not a heavy load at all for that tank. If you added the bta, clowns, and 14 other fish, then I would be more likely to vote against the addition of a bta.
Either way, if you have any question about bacterial stability, microbacter 7 by brightwells works wonders for establishing bacterial balance.