Yes it is the "principle of [the] thing." That principle being, of course, that the circumstance of having immense wealth ought not imbue a person with the ability to restrict access to protected natural resources, like waterways and beaches.

Also, "one little stretch" may apply now, but "slippery slope" comes to mind. That isn't to say it's definitely a slippery slope to "completely privatized access," but any time another Vinod succeeds at challenging the law chips away at the above principle. I'm glad he lost.