[giaour]

I would need to find data to back this up, but my sense is that much of the political difference can be accounted for with demographics.

Tech workers as a group are younger than the population at large. Tautologically, the group excludes retirees, and as the industry has expanded over the past decades, it's growth has been fueled by hiring recent college graduates. Lower ages and higher levels of education are correlated with left-wing views in polling results.

If you controlled for age and education, I don't think you would see any ideological distinctions between tech workers and the rest of the population.