This is certainly not the case. For more details do a little exploring in the link I provided above. For one, the bulk of their code is low-level, just not this particular system where it wouldn't have made sense; for two, they did this in 2002 when it was almost certainly easier to find C programmers than javascript programmers; for three, the people writing this javascript were domain experts, not professional programmers.

Some people would kill for the ability to put a 1/2-year NASA stint on the resume, if for no other reason than the idea that they contributed to the scientific research and exploration of space.