I wouldn't be surprised if that it's permanent cage until it gets larger just because of space issues and housing/breeding so many snakes in the facility.

I literally just got my first baby giant today (mainland ST) and I can say when she's full grown she won't be in a tub: I just can't fathom one that would be large enough for ANY adult dwarf/mainland retic. Mainland girls need at LEAST 6-8' enclosures, and the male in the vid should be in at LEAST a 4' viv IMO. But I'm not a breeder of course, just my .02