Yep. That's right. The chart lifespan figures are rounded, of course, but should be good enough for government work.
A 30th level wizard of 19 INT, for instance, could create a beast that lives over 900 years. IMO, that doesn't seem too long for a creator of godlike ability, but a DM could put a cap on it if he wanted to.
Of course, the creator could always elect to make her beasts infertile or have shorter lifespans. The fertility & gender checks and size & age limits are just upper limits of the spellcaster's control.