CY, R’ Moshe is saying that because it was already accepted in many places in Europe to have a nochri turn on the light (lantern), the idea of having lights go on is not zilusa. He might have said the same thing about Shabbos clocks having become accepted, but that doesn’t seem to be what he actually said.
Interestingly, the prior teshuvah is about the havla’ah of bank interest, which is what I compared the prize money to.