Sorry for the late reply
I was in Manado 3 weeks ago. No problem at all. I have not stayed in town, but you won't neither will you? Diving resorts are perfectly quiet, no worry. And divers are always as friendly as usual.
I will be in Dongala (1h30 from Palu, Central Sulawesi) in 10 days. I am not aware of any diving spot in Palu itself. I made contact with my good friends there and they have not mentioned anything bad neither.
I leave all year long in Indonesia. I feel safe here, safer than in big European cities.
Few tips: stay neutral in your look, speach and behaviour, and don't go with the crowd....and smile, it opens doors.
Anyway, there is no safe place on earth anymore, and no one knows about tomorrow...so, I'd rather be underwater!