Chairman Mao's reaction is understandable as it is common knowledge that beasts mutated due to prolonged exposure to large amounts of mana are aggressive and vicious.
Even a tiny, mutated rabbit is too dangerous to be kept as pets due to their fierce nature.
Only people who manage to ask beast tamers to help tame the beasts can keep them. This costs money, time, and connection— and considering the rarity of the beast tamers in the awakener's society, only a few could afford to do it.
Of course, there are others who are spared from the hassle mentioned above. Some people are lucky enough to form a bond with intelligent mutated beasts, and a beast tamer's help isn't needed in this case.
However, this only happens on rare occasions; luck is indispensable.
It's a mystery for Chairman Mao how the Bai family brought home a wild mutated giant panda.
