Good plan. Six ATI bulbs are plenty of light for magnificas (that's what mine have thrived under), but six of your average T5s almost certainly are not sufficient. Having a fair amount of experience with magnificas though, I'd say that one looks unhealthy rather than light deprived. I would definitely return it if you can. These guys are pretty delicate and really do not ship well. You have to monitor them closely for over a month after you get them and even one that seems healthy at the store and in your tank for the first few weeks can go into the dreaded deflation cycle before withering away.
Unless you could find a healthy gigantea (which is much harder than finding a healthy magnifica) your clowns are probably not going to get as excited over another anemone like they did with this one simply because BTAs and haddoni's (likely the type of carpet they have) are not natural hosts for them. There's always a chance though, so I'd recommend getting the BTA if you find one you like.