I understand you to be searching for spiritual answers primarily, not political.
This story is indeed rather a political one and does not have much to do with a spiritual quest. But it’s sad indeed.
Generally, I would say it is normal that traditions develop over time, and different traditions develop in different ways. You may perhaps be interested to read this essay by Bhante Sujato where he lists a number of points where the Theravada tradition has come to views and ideas that diverge from the early texts.
Similar things have been and still are going on in all traditions (Buddhist or otherwise), and this is just a normal feature of a living tradition. So yes, it is to be expected that in Zen (which I personally am not familiar with) you will find things that are not backed up in the Suttas.
But as Bhante also points out in his essay, we should also bear in mind that the traditions, besides having their own influences and views, also have preserved things that can not easily be captured in a text: things like respect for the Buddha and his teachings, moral values on how to live together in a good way, etc.
The Suttas—or let’s say the Early Buddhist texts, which include great portions of the Pali canon as well as their parallels transmitted in Chinese, Sanskrit, Tibetan, etc.—are certainly a good way to come as close to the original teachings of the Buddha as we possibly can; which does not mean that the spirit of his message may not equally be found elsewhere, especially in a way of living of any individual who has managed to develop a certain degree of peace and wisdom within themselves, no matter with which tradition.
So I think it is up to each of us who wish to foster spiritual values in our lives to find our own way of how we want to live and practice and what we can or want to believe.