No doubt such instances exist, but as you say, a scab is a scab with _or without_ an H-1B visa, whether s/he is a citizen, "guest worker," or illegal alien. The question is how we uncouple union organizing from anti-immigrant sentiments. In some workplaces, the majority of workers must be immigrants (close to our home, many factory farms in Ohio, for instance), many of whom are illegals. Unions can't organize them while calling La Migra on them at the same time, no? Besides, hi-tech computer industries, to take your example, can relocate wholesale, right? In fact, that's even cheaper than importing workers, given differences in living standards between the USA and India, China, Poland, etc (whether you are talking about the production of hardware or software). "Why bring them here and pay them American wages? Pay them Polish wages," or so would the ruling class think, eventually.
Max and higher-level union officials probably think that the U.S. government can, should, and will apply judicious immigration control and fair-trade economic sanctions (including import bans) to benefit American workers permanently. I'm saying the U.S. government won't. And it can't -- I think that under capitalism we at the capitalist core will either get a high-unemployment, high-wage, expensive-welfare economy (W. Europe) or a low-unemployment, low-wage, cheap-welfare economy (USA), with or without immigrants, however you control them. And the former is in the process of transforming itself into the latter, and in fact, the U.K. has already done so, to a large degree. (Japan will probably have to do so to get out of deflation and stagnation; it hasn't yet -- hence the immense fiscal stimuli and low interest rates producing little signs of robust recovery.) In any case, both are dead ends for workers.
Steelworkers and other mass production workers were once predominantly new immigrants, no? (In fact, the ratio of the foreign-born to the native-born workers was much higher in the early decades of this century than now.) But the unions organized them anyway. That's the spirit we need.
Yoshie