There was no doubt about the strength of a Beast Spirit genius. A True Immortal-level prodigy could cross two major realms to fight a Golden Immortal. Even if their comprehension of the concept and might of strange beasts was not high, they could rely on the magical power of strange beasts to seize the natural luck of heaven and earth and have a huge advantage in battles of the same level. Especially with a Beast Spirit Treasure, this advantage would be even greater.
Not to mention that the Strange Beast Gate had the secret to transcending longevity.