To the contrary. Xenophobic rhetoric never starts with large sweeping gestures. This is how it starts, as a seemingly harmless statement about facial features, stereotypes and presumptions about where they are from and to whom are they loyal.
The undertones of Dave's statement are there. Choosing to ignore them or basically say, "well I"m probably right" because of anecdotal experience doesn't lessen that. But since Dave brought it up, as an adjunct professor, I'm still on a college campus. I will be again today. And these kids are very much siding with Palestine and they are very much born and raised on US soil. Your presumption is not as harmless you think. People have used "they're not even from here" or "go back to your own country" to make Asian Americans who are born and raised here feel set a part or "othered". I would think you'd be more sensitive to the harm these type of opinions could have. Is that somehow different? Making a sweeping generalization about college kids on a college campus is different than making a sweeping generalization about Asian Americans who making a living and raised their families in the suburbs? Words do indeed have meaning.