without commenting on the truth of the statement (I don't know, I've never talked to american programmer's unions), in the US, unions have traditionally backed anti union sentiment, for example, chinese exclusionary acts in the late 19th and early 20th century.
It's rather parochial and essentialist to imagine that American labor unions are inherently anti-immigration. This country was founded by immigrants after all, and certainly more recent immigrants can bring in new innovations that can improve our current flawed institutions. Perhaps the next generation of labor unions can do better. To imagine that there is a "context of America" that is fixed and unchanging is to both deny the many cultural contributions that immigrants have brought to this country, and to deny that this country's context is perpetually changing.
True, it is a bit unfair to be prejudiced that way. But you know the famous saying: "Fool me once, shame on you. Fool me twice, shame on me". I haven't forgotten how Avalon and Peru and Excelsior came to be. And when I tried, it was brought home to me again why I shouldn't.
There is a rich irony in your evocation. As a former resident of that neighborhood, and as someone from that continent once denied, I can see that times can change. Perhaps this country has. And even labor unions, too.
Even a cursory glance at contemporary tech movements show that they are largely culturally progressive in nature. Anything from the TWC reveals that they fit in with the general leftist Bay Area political milieu:
If you think any of these groups are going to produce something that can be turned into a nativist movement, then you don't seem to have a clear idea about the state of modern politics.