Apparently, Carl Thayer is considerably more "authoritative" and better-known than you realized. Read this recent New York Times report:
In which, Thayer provides the quotes:
“It’s changing the status quo,” said Carlyle A. Thayer, an emeritus professor of politics at the University of New South Wales in Australia. “It can only raise tensions.”
And the concluding quotes at the end of the report:
“None of this is an isolated incident,” he said. “It seems to be a new plan to assert Chinese sovereignty. This isn’t something that will go away. This is a constant thing that will raise tensions, and at the same time no one has a good response to it.”
Reading most of the reports and articles from western media on SCS, you realized that most of the quoted people are westerners or westerners based in the region, presumably providing some "regional" perspective or voice. Occasionally, they would have quotes from some anonymous "Asian diplomat" speaking out against China. Strange thing is other than Vietnamese or Philippines, you don't hear very often from other Southeast Asian countries. So I guess the regional positions are represented or spoken for by the western media or analysts.