Although Buddha is a belief in everyone's heart, even now many people still have porcelain statues such as Guanyin in their homes, and ancient queens and queens will go to temples to worship Buddha when they are unwell, and some even go to temples for retreat. They bowed down to the Buddha and prayed for his protection, but the emperor never bowed down to these things. Not because the emperor didn't believe in these things.
However, the emperor is the embodiment of the real dragon emperor. They can ascend to the throne because there are other gods protecting them besides their own abilities, such as dragons, which is why the emperor's seat is called the dragon chair and his clothes are called the dragon robe. These are well-founded. The emperor is busy with government affairs, so he can't fast and recite Buddha every day like the women in the harem. The master of a country is the reliance of its people. If you believe in these things all day, then this country may not be far from being shattered.
And as the emperor of a country, there are bound to be many assassinations. They won't believe anything when they come to the throne. They will suspect the people around them and outsiders. People in the palace try poison first and then taste it, so the emperor will not believe in Buddhism.
Of course, we can't kill everyone with one stick. Some emperors may believe in Buddhism, but as long as the Buddha has this idea, there are some things that need not be taken, which will only make the world laugh. If you are the king of a country and always go to the temple to worship Buddha, what will the people think and the ministers think? They will only think that the emperor is incompetent and has no decisive ability to do things, and they must rely on the help of the Buddha to solve the problem. So there is a reason why the emperor doesn't bow down to the Buddha statue.