Why? I don't think that it's really even speaking to the individual values. My interpretation is that it's making the (unsupported) assertion that the entiret

Why? I don't think that it's really even speaking to the individual values. My interpretation is that it's making the (unsupported) assertion that the entirety of those values represent the pinnacle of what appears to be normal or culturally appropriate, from the perspective of typical white Americans. So for example, if you say to a white American, "tomorrow will be better," that's an uncontroversial position to take. Or, "my kids each have their own bedroom," seems like a fairly normal and uncontroversial expectation. Whereas if your behavior goes broadly against these norms, say, "My kids all sleep in the bed with me," or "I just go with the flow, professional advancement doesn't interest me," then you will seem out of step with what (white) society deems as most appropriate. It's not saying that all of these values are exclusively the purview of white Americans, nor is it saying there's anything wrong with these values. To the extent that anything is implicitly discouraged, I would venture that it discourages taking for granted that cultures that diverge from this specific value set are inherently defective. Also, this comes from 1990. A lot has changed since then. Maybe it's not quite as controversial to be non-Judeo-Christian, for example.