"Foreign language teacher" isn't a "highly specialized skill"? Tons of Americans work as English teachers abroad.
They work abroad under the respective country's work visa. H1B is US specific, specific visa. The US has plenty of other work visas.
The law doesn't work based on your beliefs.
> someone who knows two languages isn't remarkable, someone who can teach others isn't remarkable
First: it depends on the language.
Second: the combination of two relatively commonplace skills in one person isn't commonplace. "Be top 20% in two things instead of top 5% in one thing" is standard career advice.