The Buddha recognized this and, by way of his virtue, he saw the opportunity to transform them from ignorance to wisdom. This is purely related to the teachings of virtue and not an act of protest. There was no aggressive reaction by the Buddha, no hostage taking or burning of automobiles.
The Buddha's action was not in protest, but out of virtue.
Standing in between two warring kingdoms points to selflessness. It points to the difference between mundane and true compassion. This manner of virtue makes one reflect upon their own behavior.
When a Buddhist cultivator faces death, does he plead with his murderer, or simply stretch out his neck? Pleading for life is pointing to the belief in the view of a "self", an "I", other beings and a life. Is this not exactly what one must put down?
When the Buddha spoke of the "Dharma Ending Age", did he not point to the fact that within the Sangha there will be those who claim to be cultivators of the way, but be demons wearing "left home" clothing?
Any attack on Buddhism does not come out of the blue. There are causes and conditions for such an outcome. Only Buddhist practioners can deteriorate Buddhism.
What function does protesting to protect Buddhism have if one cannot pinpoint what is or is not Buddhism? A statue, monk's robes, bowl, beads, a temple with cultivators? Is that Buddhism? Those things can be taken away. They can and do deteriorate.
There is nothing more for a Buddhist to do except cultivate virtue, morality and maintain their vows of cultivation. Be good people, teach others, be wise and compassionate, patient.
Protesting is not patience. Burning cars is not compassionate, and taking
hostages to make a point is not wise. It turns the masses heads and causes them to disregard great teachings.
One good question to ask is, "Who sees?" Only those who practice virtue.