The "nearly all of them have day jobs" seems to clearly refer to the 100 engineers mentioned earlier in the paragraph. I think trose's description of them as wo

The "nearly all of them have day jobs" seems to clearly refer to the 100 engineers mentioned earlier in the paragraph. I think trose's description of them as working professionals is probably correct. The 25 students would not be considered engineers -- in fact, it doesn't even sound like they're studying to be engineers.