DY, could you explain how it was ever mutar to ask a goy to turn on lights?
I think they were meikil on amira l’akum even on a d’Oraisa (havara – the glowing filament is considered aish) for mitzvah d’rabbim (public shalishudis). I have to check back on the teshuvah. As I recall, R’ Moshe wasn’t accepting the heter, he was saying that since l’maaseh it was done (probably before timers were in common use or even invented) it leaves the realm of zilzul Shabbos.